The Solar System and Back

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ja&T 508

Asimov

As4so 1981840

Solar system and back

C 05 I— Q£

OiZ

g PUBLIC LIBRARY Fort Wayne and Allen County, Indiana

ALLEN COUNTY PUBLIC LIBRARY

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THE SOLAR SYSTEM AND BACK

ESSAYS

ON SCIENCE

by Isaac Asimov

ONLY A TRILLION FACT AND FANCY

VIEW FROM A HEIGHT ADDING A DIMENSION

OF TIME AND SPACE AND OTHER THINGS

FROM EARTH TO HEAVEN IS

ANYONE THERE?

SCIENCE NUMBERS AND

I

THE SOLAR SYSTEM AND BACK

THE SOLAR SYSTEM AND BACK BY ISAAC ASIMOV

volume are reprinted from The Magazine of Fantasy and Science Fiction. Individual essays appeared in the following issues: All essays in this

Nothing

The First Metal The Seventh Metal The Predicted Metal The Seventh Planet The Dance of the Sun Backward, Turn Backward— Counting Chromosomes Little Lost Satellite

The Terrible Lizards The Dying Lizards Little Found Satellite The Planetary Eccentric View from Amalthea The Dance of the Satellites Uncertain, Coy, and Hard to Please Just Right The Incredible Shrinking People

©

March, 1959 December, 1967 January, 1968 February, 1968 March, 1968 April, 1968 May, 1968 June, 1968 July, 1968 August, 1968 September, 1968 October, 1968 November, 1968 December, 1968 January, 1969 February, 1969 March, 1969 April, 1969

1959, 1967, 1968, 1969 by Mercury Press, Inc.

Library of Congress Catalog Card

Copyright

©

Number: 78-

1970 by Isaac Asimov

All Rights Reserved Printed in the United States of America

To—Howard

Gotlieb,

curator extraordinaire

19& 1840

Digitized by the Internet Archive in

2011

http://www.archive.org/details/solarsystembackOOasim

CONTENTS INTRODUCTION

I

ix

- THE SOLAR SYSTEM A

— 1

2 3

4

B

— 5

6 7 8

The Inner System

— — — —

THE SEVENTH PLANET

5

THE DANCE OF THE SUN

lO.

BACKWARD, TURN BACKWARD—

33

LITTLE LOST SATELLITE

47

The Outer System

— — — —

LITTLE FOUND SATELLITE

63

VIEW FROM AMALTHEA

77

THE DANCE OF THE SATELLITES

91

THE PLANETARY ECCENTRIC

IO4

AND BACK

II

A

— 9 10

Physics

— —

JUST RIGHT

123

THE INCREDIBLE SHRINKING PEOPLE

136

THE SOLAR SYSTEM AND BACK

Vlll

B

— 11

12 13

C — 14 15

16 17

Chemistry

— — —

THE FIRST METAL

151

THE SEVENTH METAL

164

THE PREDICTED METAL

1JJ

Biology

— — — —

THE TERRIBLE LIZARDS

191

THE DYING LIZARDS

205

COUNTING CHROMOSOMES

2l8

UNCERTAIN, COY, AND HARD TO PLEASE

232

INTRODUCTION

Writing the essays that

fill

this

book and

its

predecessors,

and

appearing in book form, are to be found in each

that, prior to

The Magazine of Fantasy and Science Fiction, has certain game to me. The game is this: I do my best to treat a subject accurately and

issue of

aspects of a

concisely

and the readers do

The readers I make the

their best to catch

is

happened more than twice cases.

want

errors.

a disaster that precludes republication of

a particular essay altogether, but I'm

I

out in

necessary corrections in public.

Occasionally, there

now

me

often score points, though rarely disastrous ones, and

to take

Where can

I

happy

to say that hasn't

in over ten years of essay writing,

back the adverse decision

do

this better

in

and

one of those

and more happily than

in the

introduction to one of these collections?

The

essay in question appeared in early 1959.

Here

it is:

NOTHING The word "vacuum" comes from "empty."

(We

the Latin vacuus, meaning

run close to the original in nonscientific lingo, too,

THE SOLAR SYSTEM AND BACK

X as is

when we empty This

in theory,

is fine,

we mean

a

is

accustomed

vacuum

"vacuous stare.") Consequently, a vacuum

talk of a

space, or space that contains nothing.

and we

volume of space with

to.

The

question

Or, to put

exist?

less

matter in

we

than

it

Does a

though:

is,

another way:

it

vacuums when

talk easily of

true,

all

are

ideal

there such a thing

Is

as nothing?

In between atoms of a gas there sense (there

may be

is

no matter

in the ordinary

we can

speak

raise ourselves

above

stray electrons or neutrinos) so

of an "interatomic vacuum." However,

if

we

the atomic level and consider a reasonable volume of the universe, say a cubic centimeter,

then the question of a vacuum

grows more interesting.

For instance, at

sea-level pressure

and 20

C.

(68° F.), air

has a density of 0.0012 gram per cubic centimeter. This means that every cubic centimeter contains 2.5

gen and nitrogen. Almost

X

10 19 molecules of oxy-

the mass of the molecules

all

is

in the

protons and neutrons (together called nucleons) in the nuclei of

the atoms making them up.

The oxygen molecule

contains 32

nucleons and the nitrogen molecule has 28. There are four nitro-

gen molecules for every oxygen molecule in the atmosphere, altogether, ordinary air contains 7.25

X

10

20

so,

nucleons per cubic

centimeter.

In the laboratory,

from which nearly

it is

all

possible to prepare a

the air has been evacuated. This

is

called

of

only about a ten-billionth the original quantity.

That's not bad, you understand, but even such a

vacuum

is

man-made vacuums the amount

a vacuum, and in very good air left

volume of space

retains

about 7.25

X

10

10

man-made

nucleons per cubic centimeter.

That's nearly a hundred billion nucleons in every cubic centimeter

and that sounds

Of times

as

though

there's

still

course, the science-fiction reader this.

After

all,

thins out,

There as

and

is

a bit of

knows

crowding going on.

a trick worth several

always the "vacuum of outer space."

we move up away from at a height of

the Earth, the atmosphere

200 miles or

so, it

becomes

a

vacuum

INTRODUCTION that

is

at least as

a height

still

good

as

any we can make in the laboratory, and at

vacuum

greater, the

propriate jargon,

it is still

is still

is

is

vacuum com-

a fine

we can manage,

pared to the miserable specimens

from nothing. There

better (or to use the ap-

"harder").

But even though interplanetary space far

XI

it

is

still

the debris left over from the dust and

gas out of which the solar system was formed. In fact, even in

the vast reaches between the

interstellar space,

from the

debris left over

still

formation of the raise

Sun

stars.

The

there

stars,

is

and gas used in the matter is thick enough to

original dust

interstellar

obscuring black clouds out in the galactic arms, where our

compared

located and where most of the dust exists (as

is

with the comparatively dustless galactic center).

The

case

is

similar for other galaxies.

The

average density of matter in interstellar space

is

io~ 21

gram per cubic centimeter according to some (necessarily rough) estimates I have seen. This would amount to only 1000 nucleons per cubic centimeter. Interstellar space is a vacuum that is nearly a hundred million times as hard as any we can manage but it obviously isn't nothing.

we have one more

Still,

trick to play.

dous distances between the

What

about the stupen-

galaxies, distances that

dwarf the

al-

ready tremendous stretches between the stars within a galaxy. Surely, intergalactic space

space—and

But

yet,

omers

still

ought to be emptier than

even intergalactic space

is

not quite nothing. Astron-

enough

detect

some matter

there,

light reaching us

from distant

galaxies.

But it?

intergalactic space

if

The

interstellar

it is.

is

not nothing,

to leave its

how

mark on

near nothing

is

lowest figure I've seen for the density of the matter in

intergalactic space

is

(and again

I

warn you,

it's

only a rough

approximation) io~ 24 gram per cubic centimeter. This amounts to just

This (or,

about is

1

nucleon per cubic centimeter.

as close to

nothing as anything in the universe ever gets

perhaps, ever can get).

It's

so close to nothing that

it

would

THE SOLAR SYSTEM AND BACK

XU

seem

at

about

But can we

forget about it? Is

it

so close to nothing,

it

doesn't

and we needn't confine ourselves to pinches size of the Earth and imagine

large

is

Suppose we take a volume the

The Earth

with intergalactic matter.

it filled

ber of cubic centimeters, to be sure— 1.1

There would be of these

The

mass of

up

takes

X

io

27 ,

num-

a large

to be exact.

nucleon for each of those and the total mass

1

would come to 1800 grams (4 pounds).

Sun, with a volume that

Earth, would,

if

composed of

1,300,000 times that of the

is

contain a

intergalactic material,

109 grams or 2600 tons.

X

2.3

However, ter

nothing and forget

see.

space

First, it.

just call it

it.

matter? Let's

of

we can

glance that

first

unfair to try to get an idea of intergalactic mat-

it is

by using such small units of volume. The Earth, and even the

Sun, are submicroscopic dots compared to the universe, and their

volumes are beneath contempt.

We

have

space to consider. In measuring distances outside

all

our solar system, the smallest useful unit

years as the

cube which

A

minimum

unit.

is

the light-year. Surely,

we ought

then, in measuring spatial volume,

(A cubic

to use cubic light-

light-year

is,

light-year, or 9.5 trillion kilometers,

is 1

cubic light-year contains 8.5

of course, a

on each

side.)

10 53 cubic centimeters.

X

One

nucleon for each of that vast number of cubic centimeters comes

X

to a mass of 1.4

io 30 grams or 1.5

X

10 24 (one

and

a half

tril-

hard vacuums,

this

lion trillion) tons.

Now we have nothingest of trillions

of tons

And,

after

man

standpoint,

all,

something! This hardest of

all

nothings,

when

a

still

piles

volume of

really

in the trillions of

a cubic light-year

a cubic light-year, large as is

all

up matter it is

is

involved.

from a merely hu-

an insignificant fraction of the volume

of the universe.

To show you what

I

mean, consider that the 200-inch telescope

can penetrate over a billion light-years in every direction and, as

INTRODUCTION we can

far as

no way of let's

Xlii

see or photograph, galaxies stretch out.

telling yet

how much

There

is

further the universe reaches but

imagine a sphere with ourselves at the center and a radius

of a billion light-years. We'll content ourselves with this

doubt, tiny) fraction of

With

and

all

call it

(no

the "observable universe."

a radius of a billion (io 9 ) light-years, the

volume of the

observable universe can be calculated easily enough. It turns out

You a

io 27 (four thousand

X

to be 4

trillion trillion)

was right in saying that a

see, I

mere yawn-worthy speck. (Not all the universe is intergalactic

consists of the galaxies themselves.

only a tenth of a per cent of

all

cubic light-years.

single cubic light-year

is

really

some of it make up we can ignore them at

space, of course;

However, the

space, so

galaxies

this point.)

At the

rate of 1 nucleon per cubic centimeter, the

amount

of

matter in the intergalactic space of the observable universe comes

X

to 5.6

io 57 grams.

This sounds

and 5,600,000,000,000,000,000,000,000,-

like a lot,

000,000,000,000,000,000,000,000,000,000,000 grams

much is it

age

is it,

comparison to the mass of a

in

star,

X

has a mass of 2

much more

weighs

amount

is

though, on a universal scale? For instance:

than a

star?

How How much

a lot.

Our own Sun, an

aver-

io 33 grams, so the intergalactic matter star;

much, much more. In fact, the mere couple of thousand

of intergalactic matter in a

cubic light-years equals the mass of the Sun.

However, the Sun about a hundred stars in

the galaxy

is

only one of many.

billion

(io

11 )

Sun's mass to be the average for see,

stars.

therefore about 2

is

stars,

Our

galaxy contains

The total mass of all X io44 grams, assuming which

it

probably

is.

the the

As you

the intergalactic matter weighs more than the stars in an

entire galaxy;

much

But our galaxy verse,

it

is

is

more. also only

one of many. In the observable uni-

estimated that there are about a hundred billion

(io 11 ) galaxies. universe

is

The

total

therefore 2

X

mass of io

55

all

grams.

the stars in the observable

THE SOLAR SYSTEM AND BACK

XIV

So, as sive,

it

turns out, the intergalactic matter

more massive than

as massive,

if all

all

the stars in

all

is

still

more mas-

the galaxies— 280 times

the round approximations

I

have used are con-

sidered accurate.

In fact, a godlike creature from outside our universe, looking over the entire business with a casual eye, would be justified in describing

it

as

He would

be

the occasional dots of non-vacuum, as

we

nothing more than a hard vacuum.

just as right to ignore

when we

are in ignoring dust particles

describe our atmosphere as

a gas.

vacuum of intergalactic space nothing? Heck, no! If we consider only quantity— it is Is

the

practically every-

thing.

After this appeared, friend of

mine who

intergalactic gas

received a letter from a

I

me

told

was

far too

that

my

young astronomer

estimate of the density of the

high on the basis of recent data and

that the mass of dispersed intergalactic matter was probably not

more than the

2 per cent that of the galaxies.

I

sighed,

and

retired

article.

And

then, in early 1968, nine years after the article was written,

new evidence turned

up.

By measuring X-ray

from rockets above the atmosphere, Proving Ground,

New

prising quantity of hot

fluxes in outer space

scientists

at

White Sands

Mexico, decided there could well be a

hydrogen

In fact, they say, "there

sur-

in intergalactic space.

may be one hundred

times as

much

matter dispersed as a gas in the vast reaches of space between galaxies as there

is

in all the

mass of

all

is

not yet as high as the figure

I

arrived at

figuring,

ror

the galaxies combined."

by guess and by and the initial X-ray evidence may turn out to be in eror to be misleading. Still, it is enough to make me bring my

This

old article out of retirement.

And

to

make me

feel very

good, too.

THE SOLAR SYSTEM

A

— THE

INNER SYSTEM

THE SEVENTH PLANET

1

Every once in a while, as

my

blooper in one of

my

Gentle Readers know,

essays. In that case, a

write Gently to say: "Doesn't five plus four

Then

said eight!"

To

err

is

correct

an

article

a mistake.

make

A

of Readers

nine?

You

to correct gently

comes a time when

it

is

humane.

is

necessary for

me

because scientists have discovered they had

Then, unaccountably,

am

I

furious.

How

to

made

dare they

a mistake!

case

about

also

pull a

correct myself with an embarrassed giggle.*

I

human, and

But there

number come to

I

it

happened a couple of

years ago

and Tve been brooding

my essay "Round and Round and—" (which Of Time and Space and Other Things, Doubleday, made the casual statement: "Both Mercury and Venus

ever since. In

appeared in 1965),

I

turn one face eternally to the Sun.

That was

knew when is

exactly right as far as

I,

.

or anyone else in the world,

that article was written (in mid-1963 actually), but

no longer

the back of

." .

right.

it

Astronomers have changed their minds, and

my hand

to them.

They not only outdated an

but also two novels and one novelette that * See, however, the Introduction, in case

I

you skipped

article,

had written with it.

THE SOLAR SYSTEM AND BACK

6

Have they no heart? wind indeed, out of which I cannot make an

painstaking attention to scientific accuracy.

But

it is

essay,

and

some

detail.

an

ill

time

it is

As

now

for

is

deal with the seven planets

The Greeks to

stars,

among

be

Of

these

situation in

will begin at the beginning and

known

to the ancients.

and therefore included the Sun and

number. The remaining

more

Moon

which are bright

five,

star-

or less easily visible to the naked eye, are Mars,

Venus, and Mercury.

Jupiter, Saturn,

is.

I

new

to consider the

considered any body that moved, relative to the

a planet,

their

like objects

me

usual for me,

five,

three are farther from the

Sun than the Earth

This means that they move in great swings about Sun and

Earth

They can each

alike.

them be

of

between them and the Sun.

is

directly

is

at the zenith

when

the Sun

is

any bright

night

is

The

starlike object

is

this

is so,

on the other

at nadir

Earth. This means that the planet viously,

so placed that the Earth

When

the planet side of the

at zenith at midnight.

which

is

Ob-

high in the sky at mid-

easy to observe.

Venus and Mercury, which are is. They can never be in such a position that the Earth is directly between them and the Sun, because the Earth would then have to be closer to the Sun than they are and that is not so. This means that Venus and Mercury case

is

quite different for

Sun than the Earth

closer to the

can never be seen in the night sky at the zenith. It is

can happen, on the other hand, that either Venus or Mercury

more

and the Sun. This is and each planet is then closer to the other times. Venus will be as close to us as

or less directly between the Earth

called "inferior conjunction"

Earth than

it

ever

is

at

25,000,000 miles and Mercury as close as 49,000,000. trouble

is

look in the direction of the Sun and everything

Of Sun, side

course, it

The only we must

that in that case, in order to see either planet

will

if

either planet

is

is

lost in

the glare.

exactly between ourselves

show up against the Sun's

disk.

But then

away from us (and toward the Sun) that

is

lit

and the it

is

the

by sunlight,

THE SEVENTH PLANET and

all

we

see

7

the black disk of the night side against the bright-

is

ness of the Sun.

But travels

let's

Venus

concentrate on

about the Sun.

We can

to begin with,

start

with

it

and follow

its

at inferior conjunction

between ourselves and the Sun. Steadily, as

Sun.

moves in its orbit, Venus pulls away from the and in the same direction, but Venus moves

it

(We move

also,

more quickly than Earth does, being closer to the Sun's pull.) As moves away, we can see around the night side a trifling bit and

it

the edge of the sunlit side (as seen through a telescope) looks like a thin crescent.

The farther it gets away from the Sun, the more of the sunlit we can see and the thicker the crescent. Finally, the imaginary

side

Venus

line connecting

to the

the imaginary line connecting

Venus

Sun comes to be at right angles to Venus to the Earth. We then see

"in profile" so to speak. Half of the face

the other half

is

The

dark.

planet

is

we

see

is

sunlit,

in the "half-Venus" phase

(see Figure 1).

Let's freeze matters at this half-Venus phase for a while.

point in

its orbit,

distance of 47

Venus

is

planet

"maximum

at

as far as

Now let's go on in its orbit,

it

At

this

separated from the Sun by an angular

viewed from Earth).

(as

station, this is

is

Venus can

From our

earthly viewing

The

possibly get from the Sun.

elongation."

and allow Venus

to

move

again.

As

it

continues

begins to curve away from us and back toward the

Sun.

We see

more and more of the

sunlit side as

far side of its orbit, until just before it passes

side

toward us

could see

it

is

at

fully

all,

lit

up.

it

moves along the

behind the Sun, the

We would then see "full-Venus"

which we couldn't,

have to look directly at the Sun to see

for it.

if

we

once again we would It is

now

at "superior

conjunction."

But then

it

moves away from the Sun

changing from full-Venus back to at half- Venus

it is

at

maximum

in the other direction,

half-Venus as it goes.

elongation again, 47

,

When

it is

but on the

THE SOLAR SYSTEM AND BACK Figure

1

Orbit and Phases of Venus

AT SUPERIOR CONJUNCTION AT MAXIMUM ELONGATION AT MAXIMUM BRIGHTNESS 4. AT INFERIOR CONJUNCTION

1. 2.

3.

other side of the Sun. Again a narrowing crescent until

moves toward the Sun, becoming directly between us and the Sun

it

it is

again. Let's see

what

a 47

maximum

makes one complete turn through 15

in

1

360 (

)

elongation means.

in 24 hours,

hour. It turns through 47

The Earth

and therefore turns in 3 hours

and 8

minutes.

Suppose, then, that Venus

Venus would

still

be 47

is

east of the Sun.

47 it

would shine out

before any but the very brightest stars makes star.

sunset,

above the western horizon (halfway to

zenith). In the darkening twilight

the evening

At

its

brilliantly

appearance. It

is

THE SEVENTH PLANET

9

But three hours after sunset, the turning Earth has caught up it and it sets. Venus can never be seen, in the ordinary man-

with

ner of speaking, higher than halfway to zenith, or for longer than three hours after sunset. (Venus

when

occasion

the Sun

and only

to look

is

is

bright enough to be seen on

in the sky,

just barely. Let's

but only

if

you know where

not count that, nor

let us

count

observation by specialized instruments in broad daylight.) If

Venus,

tion,

as evening star,

is

anywhere but

at

maximum

elonga-

lower in the sky and can be seen for correspondingly

it is

shorter times after sunset.

When Venus is at maximum Sun; that

is,

to

its

elongation on the other side of the

west, the situation

hours before the Sun and

isn't

morning, however, and Venus

is

different. It sets three

seen in the evening at rises in

all.

Comes

the east three hours before

the Sun and reaches a point halfway to zenith by sunrise. Before sunrise

it is

shining brightly in the

dawn

morning

as the glorious

star.

It

took the ancients some time to see that the evening star

and the morning tually

star

were not two different objects.

borne in on observers that when the evening

It

star

was evenwas

ent in the sky, the morning star was absent, and vice versa. also

noted that when the evening

there was a wait of several days

star

moved

The

They

close to the Sun,

and then the morning

peared close to the other side of the Sun.

pres-

star ap-

two were seen to be

a single planet.

Next,

let's

situation

much

of

is

it

frustrating.

Then, gets to

it

as

When Venus

can be seen as possible,

the Sun and

only see

consider the phases of Venus. In a way, the phase

is

therefore

is

it is

well

full so

on the other

some 150,000,000 miles away.

that as side of

We

can

as a comparatively tiny object. it

approaches close to us on this side of the Sun and it is at maximum, we see Venus gets, the less of its visible Venus is covered by a perpetual cloud

be at only one-sixth the distance

The

mostly the dark

side.

surface

(Of course,

is

near the

sunlit.

closer

10

THE SOLAR SYSTEM AND BACK

layer so that

we

can't see anything anyway, but

of the thing that

As

is

it's

the principle

so exasperating.)

a result, in considering the brightness of Venus,

take into account two opposed effects. As us, it gets

dimmer because it

turns out that

fat crescent stage,

At that moment

junction.

We

Venus

maximum

between

have to

is

times as bright as Sirius, the brightest

is

The mere

it

is

in a

is

is,

in fact, the third

by the Sun and the

said to

be bright enough

dim shadow.

fact that

an important

some com-

when

—4.3, or just about ten

star. It

and, on a clear, moonless night

to cast a very

from

and brighter

elongation and inferior con-

magnitude

its

we must

farther

strike

brightest

brightest object in the heavens, surpassed only

Moon,

moves

of increasing distance,

because of increasing sunlit area.

promise and

it

Venus's phases

exist at all,

however, played

role in scientific history.

In 1543, Copernicus advanced the heliocentric theory of the solar system, suggesting that the planets, including the Earth, re-

volved about the Sun, instead of having

all

the planets, including

the Sun, revolve about the Earth.

took nearly a century for the Copernican theory to be ac-

It

cepted by astronomers generally. Usually, this

is

looked upon as

a measure of the bigotry and general nastiness of Big Science, but it

wasn't.

ient

way

The Copernican

mathematics was a bit system.

mean

To

it

theory was a somewhat more conven-

of calculating planetary positions into the future.

Still,

because

easier

it

The

than in the case of the Ptolemaic

was a mathematical shortcut, did that

also portrayed the solar system as

it

was?

consider Copernicanism physically true as well as mathe-

some observational evidence was needed, not show any parallax, as have done if the Copernican theory were correct, it

matically convenient,

and none

existed! In fact, since stars did

they ought to

could be argued that there was at least one piece of observation that was against Copernicus. (Copernicus maintained that there

were indeed parallaxes but they were too small to be measured.

THE SEVENTH PLANET

He

was

right,

11

but the observational evidence for that was not

col-

lected until three centuries after his death.)

Without

why

observational evidence,

should anyone believe

that the firm Earth beneath his feet was flying about the

without his being aware of century,

I

it?

Had

I

been

Sun

living in the sixteenth

wouldn't have believed any such cock-and-bull

story,

either.

But then came Galileo and found that Jupiter had four

he

his telescope. In January, 1610,

satellites circling

of blow to the Ptolemaic view since

it

it.

This was a kind

showed that there were

at

least four objects in the

heavens that were manifestly circling some

body other than Earth.

It

was not

be maintained that Jupiter and

tem that

circled the Earth.

would be

affected.

It

its

No

was Venus that was the

fatal,

though, for

it

could easily

four satellites were a single sys-

other point of Ptolemaic theory

crucial planet.

The

only

way the

Ptolemaic theory could have Venus traveling about the Earth

and

still

move

in the heavens as

it

did (using the orbital mecha-

nisms they insisted on using) was to arrange matters whereby

Venus

oscillated

back and forth from one side of the Sun to the

other, while always remaining

mean

between the Sun and the Earth.

Venus would always be at half-Venus or less; it would always be some sort of crescent, thick or thin. On the other hand, by Copernican theory, Venus would travel completely around the Sun, and therefore, as described earlier in the article, would display all the phases from new to full, in just the manner our own Moon does. In 1543, there were no telescopes and no one could tell whether Venus showed phases at all, let alone what kind. So when Copernican theory was born, the phases of Venus could not serve as

This would

that

observational evidence.

But then, covered the

in September, 1610, eight satellites of Jupiter,

Venus and found

it

more than

months

after

he had

Galileo turned his telescope half-Venus.

dis-

on

THE SOLAR SYSTEM AND BACK

12

Galileo was enough of a scientist not to want to rush into print half-cocked. It was important that he follow orbit

and make sure that

its

On

according to Copernican predictions.

enough of

a self-centered

human

for the discovery simply because

He little

Venus

all

through

its

phases followed in order, precisely the other hand, he was

being not to want to lose credit

he was being cautious.

therefore published the following Latin sentence in

the

newsletter he was putting out concerning his investigations:

Haec immatura a me iam frustra leguntur, o. y. This means "In vain were these things gathered by me today, prematurely." This is a sort of dim hint that he was onto something he was not yet ready to disclose, but the sentence was an

anagram and when the ture of his discovery.

the anagram

letters

(The

come out

were rearranged

"o. y." at the

it

gave the true na-

end was needed to make

correctly.)

Rearranged, the sentence went:

Cynthiae figuras aemulatur

mater amorum. This means "The mother of love imitates the appearance of Cynthia." This scarcely seems clearer but figurative in

an age

in

which

Galileo

intellectual society

knew

was being their

Greek

myths.

To

begin with, Apollo and Artemis were born on Mt. Cyn-

thus on the island of Delos, according to the myths, and were therefore sometimes called Cynthius

and Cynthia

respectively.

Artemis was commonly considered to be a representation of the

Moon. Consequently, Cynthia As

for the

"mother of

love,"

is

a classical epithet for the

who

Moon.

could that be but Aphrodite

(Venus), the mother of Eros ("love"). So, in effect,

what Galileo was saying was: "Venus

phases like those of the Moon," which

is

displays

what the Copernican

theory required and the Ptolemaic theory forbade.

That

settled Ptolemy's

hash and put Copernicus

in business,

except for the inevitable die-hards (mostly, but not entirely, non-

astronomers).

THE SEVENTH PLANET Although Venus can be seen only

13

for limited periods

after

sunset or before sunrise, those limited periods are long enough to

allow

Venus

If a

to be a prominent object indeed.

planet

Greek

considered, in

is

moves against the background of

be any body that

fashion, to

stars,

then

have no doubt that

I

Moon was the first planet to be discovered, for observation the Moon on any two successive nights is enough to show that

the of it

has moved against the stars. The Sun would have been the second

became

planet discovered. It soon

clear that the starry pattern of the heavens shifts

from

night to night, and that would have been blamed on the ap-

parent motion of the Sun against the it

Such motion causes

stars.

to blot out a gradually shifting half of the sky.

But then the

Venus

less

notable planets were detected, and of these

headed the

surely

It is

list.

by

particularly brilliant in the dying twilight

beginnings of presenting

The

dawn when the Venus with

and with respect Call

Venus the up

to

in the glimmering

other stars are washing out and

respect to the

to the other stars,

it is

Sun

is

soon obvious,

only slightly

less

obvious.

third planet, then, historically speaking.

Mars, Jupiter, and Saturn are heights,

and

it is

competition.

little

shift of

and

far the brightest;

and including

all visible in

zenith.

Of

the night sky at

these, Jupiter

is,

all

on the

average, the brightest, over twice as bright as the star Sirius.

However,

for a short

as Jupiter and, it is

on

time every other year, Mars

rare occasions, even a bit brighter.

the background of the stars some does. It seems to

as bright

more eye-attracting than Furthermore, Mars moves against

of a distinctly reddish color that

the ordinary white of Jupiter.

is

What's more,

six

is

times as rapidly as Jupiter

me, then, that Mars must have been the fourth

planet to be discovered.

Saturn quickly.

is

dimmer than

So Jupiter

order of discovery.

is

the

Jupiter

fifth

and moves

less

than half as

planet and Saturn the sixth in the

THE SOLAR SYSTEM AND BACK

14

That leaves Mercury which, I maintain, was surely the seventh and last planet to be discovered by naked eye. Why? Well, it is the nearest planet to the Sun, nearer even than Venus, which

means that it shows all the more pronounced fashion. Because

move

it is

as far

maximum

about 27

is

That means

zenith.

Sun than Venus

closer to the

is,

it

doesn't ever

from the Sun (from our Earth-based view)

does. Mercury's

conditions

Venus, but in

orbital peculiarities of

it

,

as

Venus

elongation under the most favorable

or less than one-third of the

can only be seen at most for

way

to the

than two

less

hours after sunset or before sunrise. In

there

fact,

is

another

is

least elliptical while Mercury's, of

those planets visible to the naked eye,

The Sun

is

which means

The more

the planetary orbits are

difficulty. All

but Venus's orbit

ellipses,

most

is

elliptical.

always at one focus of the planetary orbital it is

ellipse,

nearer to one side of the orbit than the other.

eccentric the ellipse

and the

less nearly a circle,

the

(and therefore the Sun) to one side than the

closer the focus

other.

In the case of Venus, the eccentricity for is

an explanation of

"eccentricity.")

is

0.0068. (See Chapter 8

This means that the Sun

66,750,000 miles from one side of the orbit and 67,650,000 miles

from the other

Venus

gets

cedes from

side.

to the it

These distances are, respectively, the closest Sun ("perihelion") and the farthest it re-

The difference is only 900,000 miles. maximum elongation, it may happen to

("aphelion").

When Venus

is

at

its

be at perihelion or at aphelion or anywhere if

it

is

at perihelion

smaller

maximum

ference

is

it

is

closer to the

elongation than

so small, however, that

if it it

in between. Naturally,

Sun and has

a slightly

were at aphelion.

The

dif-

can be neglected for ordinary

purposes.

Not

so in Mercury's case. Its orbital eccentricity

Mercury

When

it

is

closest to the

is

farthest,

it

Sun is

again as far as perihelion.

it is

is

0.21.

When

at a distance of 28,500,000 miles.

43,500,000. Aphelion distance

is

half

THE SEVENTH PLANET That means there

mum

elongation

is

15

a tremendous difference between a maxi-

when Mercury happens

to be at aphelion

and

one when above, all

is

it happens to be at perihelion. The figure of 27 given , an elongation at aphelion and represents the greatest of

maximum elongations. maximum elongation

possible

At

perihelion, the

ten minutes after sunset or

rises

under 18

just

is

Mercury hugs the horizon and

these times,

.

At

an hour and

sets just

an hour and ten minutes before

sunrise.

And mind and

you, these viewing times of

hour at some times

1

moment

2 hours at other times are only at the

of greatest

elongation, say two or three nights in every 3-month period.

other times, Mercury

all

Sun and

closer to the

is

is

At

viewable for

smaller periods.

We can summarize by saying that Mercury when

it

is

is

hardly ever visible

(Astronomers use special instruments to

truly dark.

no help to a naked-eye observer like an ancient Greek or a modern me.) What's more, Mercury has other disadvantages as a viewable

observe

object.

it

in the daylight

To be

but that

is

sure, it is closer to the

of

Sun and

is

more

brightly

square mile for square mile, than are other planets; but smaller than

Venus and

gets less total light.

Where Venus

it

lit,

is

has a

diameter of 7,550 miles (almost that of Earth), Mercury's diameter is only 3,030 miles. Mercury is, in fact, the smallest of the planets.

Then,

too,

the light that

Venus has falls

upon

atmosphere and must the

Moon

like

the

does.

Moon,

There reflects

it.

only about

both at their brightest, Mercury

Add

Venus all

of

from

its

bare rock surface as

every reason to suppose that Mercury,

Finally, in the crescent stage, at

us than

%

Mercury, on the other hand, has no

reflect light is

some

a cloud layer that reflects

is

%4

of the light

it

receives.

which Mercury and Venus are considerably farther away from

is.

these things together—that

Mercury

is

smaller than

THE SOLAR SYSTEM AND BACK

l6

Venus,

and

farther away,

is

prising that

Mercury

is

light— and

reflects less

much

dimmer

the

not

sur-

of the two. Mercury, at

very brightest, has a magnitude of —1.2 and

its

is

it

is

y17

only

as

bright as Venus. It is

not the least bright of the planets. Saturn has a

when Mercury

brightness of —0.4, so that

at

its

best

maximum twice

it is

However, Saturn can be viewed in the calm

as bright as Saturn.

darkness of the middle of the night

the heavens and where

when

be seen only near the horizon

in

it

may well be high in among the twenty

out as

will stand

it

brightest stars or starlike objects. Mercury,

Sun

is

dawn

on the other hand,

or twilight,

will

amid haze and

glare.

There

is

no question

in

my

mind, therefore, that Mercury was

the seventh planet to be discovered.

people today (when the horizon the sky

much

There

is

is

much

and

dirtier it

was

have never seen Mercury.

even a story that Copernicus himself never saw Mer-

though

There

is

many

suspect, in fact, that

generally

hazier with the glare of artificial light than

in centuries past)

cury,

I

I

can hardly bring myself to believe that.

a curiosity here that

some Gentle Reader points

it

I

would

like to

point out before

my

discussion of the

out to me. In

seven metals of the ancients later in this book (see Chapter 12) I

point out that the metal mercury was probably the seventh

and

last

metal to be discovered by the ancients.

And

here

I

say

that the planet Mercury was the seventh and last planet to be discovered, so that

Furthermore, for the planet

I

it is

entitle this chapter

known

Mercury.

metal was named know more than

"The Seventh

Is it entirely a

named

coincidence that the seventh

Or

for the seventh planet? is

Planet."

that the metal mercury was

generally thought,

did the alchemists

and did they know the

order of discovery of metals and planets and arrange the names to correspond? I

know

there

lieve in the

is

a strong tendency

on the part of mystics to be-

"wisdom of the ancients" but

I

don't think they were

THE SEVENTH PLANET The correspondence between

that wise.

all

a coincidence, in

my

are such things as pure coincidence,

and

seventh planet

How

is

long does

Sun? At

first

seventh metal and

opinion. After this

take for Mercury and

it

blush,

17

is

Venus

The

planet

then have started at the point between ourselves and the Sun,

gone

come back

around, and

all

and the Sun. It takes Mercury 116 days is

around the

to go

might seem that one need only count the

it

days between one inferior conjunction and the next. will

there

all,

an example.

to the point

do

to

this

between ourselves

and Venus 584

days. This

the "synodic period of revolution." It

however, a

is,

strictly

Earth-related period. After

the

all,

moving around the Sun, too. If Mercury starts at a certain point directly between ourselves and the Sun, then moves around the Sun back to the same point (recognized by its position relative to the stars), it will turn out that the Earth is no longer where it was. It has gone its own way and, since Mercury left, has Earth

is

completed about one-quarter of

its

own

revolution.

Mercury must continue turning until it catches up with Earth and gets in between it and the Sun again. Mercury, which is so

moves

close to the Sun,

faster

than any other planet relative to

(30 miles per second, as compared with our

second).

we

calculate

in

in

88 days. This

usual period

The

we

situation

long

it

takes

Mercury

to return to the orig-

own motion

it

turns out that Mercury revolves about the

is

the "sidereal period of revolution" and

in

Sun

is

the

Venus. In the

first

speak of as the "length of Mercury's year." is

more extreme

in the case of

place,

Venus

make

a longer sweep to go about

is

us, there-

about a month.

how

inal spot relative to the stars, regardless of our

the interim, then

it

18.5 miles per

does not take very long to catch up with

and does so

fore, If

It

own

farther

from the Sun than Mercury it.

It

is

and must

moves more slowly than

Mercury does (only 22 miles per second) and takes a much longer time to

make the

greater sweep.

THE SOLAR SYSTEM AND BACK

l8

By

the time

it

returns to

its

original point relative to the stars,

Earth has had a long time to move on

its

orbit

and has gone

three-fifths of a revolution.

Venus does not move much more quickly than the Earth does it can gain on us only slowly. It must make a second full turn about the Sun and then a half-turn before it catches up. If we count only the time it takes Venus to go around the Sun with reference to the stars and disregard the moving Earth, then the sidereal period of revolution of Venus turns out to be 225 days. and

Which

brings

me

two planets about

finally to

the matter of the rotation of these

their axis, old view

and new view, and we

continue with this subject in the next chapter.

will

THE DANCE OF THE SUN

2

Occasionally

I receive

one that was

rather depressing letters. Once, I received

and

several pages long

but the beginning was clear enough. of

It

largely incomprehensible,

objected strongly to a book

mine on astronomy.

The

writer claimed that

tant matter,

my

showed

I

had neglected one supremely impor-

and the implication was strong that

incompetence.

He

complained that

I

this

neglect

had spent much

time describing the universe and trying to give a picture of then

totality,

left

out the key point.

up?" he demanded. it

from

The

"Why

what keeps

proper answer would have been: "Fall where?" but that just gotten

him angry without

I tried

to read his explanation of

falling,

an explanation

I

this

mind

is

just

after

enlightening him. After

what kept the universe from

couldn't understand,

thing was not to answer at

zles

holds the universe

didn't you try to figure out

falling?"

would have

But

"What

its

I

decided the wisest

all.

one example of the type of question that puz-

mind and which no explanation seems

to answer

properly.

There are always people who

aren't satisfied that the law of

THE SOLAR SYSTEM AND BACK

20

means that

"But what

And

Moon

move

in a

vacuum.

are the exhaust gases pushing against?" they

demand.

action and reaction

there are

a rocket can

some people who

can be rotating

if it

will never

always see the same side," they say, "then Naturally, there

is

once and for

and

all. I

it

an awful temptation

case of compulsive explainitis, as analysis so clear

be

the

satisfied that

always faces the same side to us. "If

(if

have)

I

we

can't be turning/'

one has an advanced

some

to try to find

so irrefutable as to explain the

whole thing

have, for instance, tackled the problem of the

Moon's hidden side on a number of previous occasions and now I'm going to do it yet again in a new way. This time, though, I have an ulterior motive. I want to do it so I can continue talking about Venus and Mercury, a subject I brought up in the preceding chapter.

To

begin with, each planet has two chief movements: (1)

turns, or rotates,

about

the Sun. First,

let's

its axis,

and

(

2

)

it

turns, or revolves,

it

about

consider the matter of rotation about the

axis.

By

convention, the axis (an imaginary line) defines north and

The

south.

axis intersects the surface of the

Earth at the North

Pole at one end and at the South Pole at the other.

Suppose, now,

we imagine

ourselves high in space, exactly over

the Earth's North Pole. Looking

down upon

the Earth, the North

Pole would appear exactly at the center of the planetary

(Of

Sun— a in the

little

more than

winter— and the

half in rest

we

circle.

would be lit up by the the summer, a little less than half

course, only half the circle

would be

see

in darkness,

but

we'll ignore

that as an unimportant detail.)

From our vantage see the

about

point directly above the North Pole,

whole planet turning about

its

it

we would

exactly as a wheel turns

hub.

But which way does the planet turn? There are two possible ways, and these can be most easily described by reference to the face of a clock. We all know the way in which the hands of a clock turn. Well, the normal progression of the hands from

1

to

THE DANCE OF THE SUN 2 to 3 tion,

As

on the

from it

face of the dial

is

"clockwise."

21

The

opposite direc-

3 to 2 to 1, is "counterclockwise."

happens, the Earth, as viewed from above the North Pole,

turns counterclockwise. This counterclockwise rotation, from a

view on the Earth's surface, means that our planet turns from west to

east.

You can

see this for yourself,

in your house (or,

if

you have a mounted globe

if

you are very enthusiastic, you can find one

in

the local school or library). Turn the globe from west to east, and look

down upon

see that

it,

as

it

turns,

from above

its

North

You

Pole.

will

turning counterclockwise.

it is

However, if you continue to rotate the globe from west to east and bend down so that you can see what is happening from a view over the South Pole, then you will find the Earth, from that vantage point,

is

turning clockwise.

of turning, then, you

must

To

give

meaning to the

specify the point of view,

conventional always to suppose that the view

is

direction

and

it

is

from above the

North Pole. This orientation can be applied to the solar system generally, because

it

happens that

all

the major planets are located close to

the plane of the Sun's equator, and

all

the axes of

all

the planets,

with the exception of Uranus, happen to be within 25

of the

perpendicular to that plane.

we imagine ourselves reasonably high above the North Pole of the Earth, we are also high above the general plane of the solar system. If we then move over the Sun, we would This means that

if

one end of its axis points more or less toward Sun moves counterclockwise about it. We would

find that

that the

same thing

to

be true

if

we moved

us,

and

find the

over Jupiter, Saturn, Mars, and

so on.

This represents a fine display of orderliness, clockwiseness, but

take

up

I

all

this counter-

warn you there are exceptions, which

I will

in the next chapter.

But what

if

mankind ever engages

colonizing the planets of another Sun?

north and which south?

To

refer

in interstellar travel

Which

and

pole should he

is

call

back to the plane of our own

THE SOLAR SYSTEM AND BACK

22

system would be inconvenient and, at times, useless.

solar

dict that the star itself will axis its

about which

it is

But

let's

get back to the Earth

the only motion

tion, it

A

and the Sun. The Earth

it

has.

person standing on the surface of the Earth will not

still.

its

be interpreted

As the Earth

on

its

rotat-

its

rota-

will

feel

the

seem, to himself, to be

on which he stands

is

con-

orientation with respect to the Sun, but that

as caused

rotates

by the

fact that the

from west to

surface that the

to west. Because the real

clockwise,

He

Naturally, the point

stantly changing

server

is

that this

We will suppose that, except for

planet to be rotating, however.

will

moment

motionless with respect to the Sun.

is

standing

satisfac-

planetary system generally.

its

ing counterclockwise and we'll suppose for a is

its

rotating counterclockwise will be defined as

north pole. That will almost certainly define north in

tory fashion for

pre-

I

be used as reference. That end of

east, it will

Sun moves

Sun

moving.

is

appear to an ob-

across the sky

motion of the Earth's surface

the apparent motion of the Sun

is

from is

east

counter-

clockwise (see

Figure 2).

We can measure the rate of turn as so many degrees per unit of time; say, so

many

one complete

turn.

degrees (°) per day where there are 360

in

Since clockwise and counterclockwise are rotations in opposite directions,

let's

arbitrarily

and counterclockwise turns For instance,

if

give clockwise turns a

positive

sign

a negative sign.

a planet turns counterclockwise on

its

axis ex-

one day, we would say it turned — 360 ° per day. To a person on its surface the Sun would seem to make a complete clockwise turn about the sky in one day. We could then say that the apparent motion of the Sun, resulting from the planet's rota-

actly

once

tion,

is

We

in

+360 per

day.

don't, however,

have to pin ourselves down to any one

planet moving at any one rate.

We

can talk about an arbitrary

planet which happens to be turning on

its axis

at a rate of

— x°

THE DANCE OF THE SUN From

per day.

through

Mind motion

its

its

that of turning

is

on

second important motion.

its axis.

It revolves

Every planet, however, has a

about the Sun as well.

we imagine

If

Pole, self,

Sun would seem to be moving +x° per day. for a planet whose only important

surface, the

sky at the rate of

you, though, this is

23

ourselves, now, to be high above the Sun's North and observe the planets revolving about its giant, luminous

we would

terclockwise.

see that every major planet revolves about

There are no exceptions.

these counterclockwise rotations and

(All

this

revolutions,

Figure 2 Rotation APPARENT CLOCKWISE MOTION OF THE SUN

STATIONARY SUN

WEST

EAST

EARTH

it

coun-

regularity— all

with so few

THE SOLAR SYSTEM AND BACK

24

ones—has to be explained. them that all modern theories

from attempts to

clockwise

It is

plain

of the origin of the solar

ex-

system have arisen.) Let's consider, then, a planet revolving about the

terclockwise fashion and, to this

is

Sun

let's

in coun-

pretend that

we considered that was rotating but not revolving; now we are going to a planet that is revolving but not rotating. To show that is not rotating as it revolves about the Sun, we will make

consider a planet little

same

things simple,

the only important motion

a planet

the

make

it

has. Earlier,

arrowhead, representing an observer, face always in the

direction.

As the planet from Figure

revolves about the

3 that the

Sun seems

Sun to

in this way,

move

you can see

in the sky,

from the

viewpoint of an observer at a fixed point on the planet's surface.

What's more,

as the planet revolves in counterclockwise fashion,

the apparent motion of the Sun that results

is

also counterclock-

wise.

Then,

too, the apparent

of planetary revolution, real

motion of the Sun

motion of the planet about the Sun.

in the sky, as a result

terms of degrees as the

just as great in

is

When

the planet makes

one complete turn (360 ) about the Sun, the Sun appears to make one complete turn about the sky. Suppose a planet revolves about the Sun, counterclockwise,

in

moving

at

exactly 36 days. In a rate of

— io°

for carrying

it,

1

day,

per day.

it

travels Ysq of

360

The apparent motion

,

so

it is

of the

Sun

also counterclockwise, across the sky at

is

there-

— io°

per

day.

Again, a rate of

let us

— y°

be general.

— y°

across the sky at If,

If

the planet moves about the Sun at

per day, then the Sun, in response, appears to

move

per day.

then, a planet both rotates

and

revolves (as

is

always true),

the Sun's apparent motion across the sky is +x° per day due to the rotation and — y° per day due to the revolution. The total

motion

is

Let's see

(+x°)

how

+

this

(— y°)

or,

more

briefly,

(x



y)° per day.

works out in the case of the Earth.

The

ap-

Figure

SUN'S APPARENT COUNTERCLOCKWISE MOTION ACROSS THE SKY

Revolution

O

o

o

3

*

\

O

EARTH'S COUNTERCLOCKWISE REVOLUTION ABOUT

THE SUN

THE SOLAR SYSTEM AND BACK

26

parent motion of the Sun in Earth's sky, due to Earth's rotation

and

revolution,

is

such that, on the average,

x



y

We tion

can calculate

its

y,

can

makes one comsay,

then,

that

the component of the Sun's apparent mo-

Sun

turn around the

one day

it

per day, in the case of the Earth.

360

due to Earth's revolution,

pletes in

=

We

sky in one day.

plete circle of the

it

enough.

easily

about 365.26 days so that

in just

moves %65.26 oi 360

.

The Earth com-

This comes to 0.9856

per

day.

= — 0.9856 per day, we can say then, that in the case of Earth, x — 0.9856 = 360 If we then solve for x, we find that x = 360.9856 If

y

.

.

This means that the Sun's apparent motion about the to Earth's rotation only,

turn of 360

in

sky, due more than one complete

a little bit

is

one day. Instead,

moves

it

just

about 361 °, with

that extra degree canceled by the part of the motion that

is

due to

the Earth's revolution about the Sun.

To make one would take a

turn of exactly 360

trifle less

,

due

than one day.

to Earth's rotation only,

It takes

24 hours to turn

361 °, but only 23 hours 56 minutes to turn exactly 360

We can see that this

is

so

.

by studying the motion of the

stars.

Every object in the heavens beyond the atmosphere has an apparent clockwise motion across the sky in response to the Earth's counterclockwise rotation.

The

stars,

The

stars do, as well as

the Sun.

however, have no progressive apparent motion across

the sky in response to Earth's revolution about the Sun. In the case of the Sun, the Earth is

moves about

it

bodily so that the

Sun

constantly being viewed from a changing vantage point. In the

process of this bodily motion about the Sun, though, the Earth's position with respect to the very distant stars can scarcely be said to change.

The

stars, therefore,

do not

alter their

tions at all (except for tiny elliptical motions

it

apparent posi-

takes a first-grade

telescope to detect).

For

stars then,

the apparent motion due to rotation

day, which in the case of the Earth

is 361 °

is

+x° per

per day, while the ap-

THEDANCEOFTHESUN parent motion due to revolution stars

The total motion of the make a complete turn in

per day, and they therefore 36 ) in %6i of a day, or 23 hours 56 minutes.

°

361

is

zero.

is

27

the heavens (360

And

the stars are observed, the time lapse between successive

if

crossings of the zenith meridian does indeed turn out to

hours 56 minutes. This period of time

is

be 23

therefore the "sidereal

day" (from a Latin word meaning "stars") while 24 hours

sidereal

move

The

day."

"solar

the

is

four-minute-per-day discrepancy between

day and the

day

solar

the

what makes the Sun appear

is

to

against the background of the stars.

And what happens period of



that case x

the period of a planet's rotation and the

if

revolution

its

y and x



(both counterclockwise) are equal? In y

=

o° per day.

Thus, when a planet rotates and revolves in the same period of time, the

Sun does not appear

move

to

in the sky. It remains in

the same spot constantly.

As seen from the Sun, the

planet, as

it

revolves,

would always

present the same face to the luminary. In this way, the

Sun

would always shine on the same face from the same angle, which is

equivalent to saying that the

Sun does not appear

to

move

in

the sky.

The Moon

Moon

respect to

that the

it

that a

same

Moon

is

Sun does

face to us at

might seem that

it

we

a

means that the periods

of ro-

It

Moon.

tremendous coincidence that the

periods of rotation and revolution should be equal, but, as pens, this

upon

is

a small

not

so.

The

(The

times.

mean

identical for the is

all

play the same role with

to a planet.) This does not

not rotating.

and revolution are

tation It

presents the

revolves about the Earth so that

it

gravitational influence of a large

body revolving about

itself is

hap-

body

such as to force the

period of rotation and revolution into equality.

The

greater the disparity in the size of the

closer together they are, the

tion

more

two bodies and the

rapidly are the periods of rota-

and revolution of the smaller body brought into

equality.

THE SOLAR SYSTEM AND BACK

28

The Earth

Moon, and until Sun had succeeded

has succeeded in doing this to the

very recently,

it

was taken

for granted that the

in doing so to Mercury.

Not only did gravitational theory make it seem reasonable that Mercury presented only one side to the Sun, but also observational evidence seemed to back that view. If one side of Mercury always faces the Sun as it revolves, then only that one side

ever

is

lit

up and only that one

is

If

viewed over and over again at some particular point in

relative to the

Earth then that

the same angle.

lit-up side

Any markings on

be Mercury

side can ever

seen by an astronomer peering through a telescope.

its

orbit

ought to be seen from

that side would be the

same

at

each viewing. Conversely,

Mercury

is

the visible markings are the same every time

if

viewed at some particular point in

its

orbit,

then the

planet would be proved to face one side always to the Sun. It

would then follow that the period of Mercury's rotation about its axis would be the same as the period of its revolution about the Sun.

The to the

trouble

and

that Mercury's distance, smallness,

is

Sun make

its

markings very

closeness

difficult to observe.

Nevertheless, in the 1880's, the Italian astronomer Giovanni

Virginio Schiaparelli tackled the problem. (or thought

so often that in the

time

had

to

he

it

of revolution tion

By

he had seen) the same markings felt it safe to say

took is

it

he had seen same position

that Mercury rotated

on

its

axis

to revolve about the Sun. Mercury's period

88 days (well, 87.97 days) and

be 88 days

This was accepted.

1890,

in the

its

period of rota-

as well.

It fit theory,

and

Schiaparelli

was known to

be an excellent observer. For three-quarters of a century, the

ment about Mercury's

facing one side only to the

state-

Sun was

re-

peated in every general astronomy book written.

But then, in 1965, radar waves were bounced off the surface of Mercury and the echoes were caught in receivers on Earth. From

THEDANCEOFTHESUN the nature of the echoes

it

is

waves

is

rotating or not and,

reflecting the radar

possible to

29

whether the body

tell

how

rotating,

if

fast.

It

turned out that Mercury

is

not rotating about

days but in 58.6 days, and this meant that

it is

its axis

in 88

not facing one side

always to the Sun. Mercury's Sun side and night side, so dearly

beloved by science-fiction writers, vanished into thin If this is so,

Well, If

how came

then

Schiaparelli to

make

air.

his mistake?

let's see.

Mercury

rotates

on

its

axis in 58.6 days

and does

so in coun-

terclockwise fashion, then x (the apparent motion of the Sun, due to planetary rotation)

is

equal to +6.14

per day.

The

period of

revolution remains 88 days, however, also counterclockwise, so

that y (the apparent motion of the Sun, due to planetary revolution) is — 4.09 ° per day.

The

total

apparent motion of the Sun as seen from Mercury's

surface, then,

is



6.14

4.09 or 2.05

per day. For the Sun to

make

one complete turn (360 ) at this rate would take 176 days. To put it another way, from Mercurian noon to Mercurian noon is 176 Earth days.

Do is

you notice a coincidence?

It

turns out that 176 Earth days

exactly twice the period of Mercury's 88-day revolution. Sup-

pose, then, that at particular place

some

on Mercury's surface

Exactly two revolutions the Sun again.

particular point in Mercury's orbit

And

later,

exactly

that

is

same place

two revolutions

the in-between revolutions, that place

from the Sun and

it is

planet that gets the

directly

one

under the Sun.

is

directly

under

later, still again.

In

pointed directly away

is

the place on the exact opposite side of the

full blast

of the Sun.

In this case, particular markings would show up on Mercury's lighted

side at particular points

in

its

orbit

in

every second

revolution. Schiaparelli, observing

Mercury, had a devil of a time making

out markings, and observed most earnestly

when Mercury was

at

aphelion and furthest from the Sun. Clouds, haze, heat quiver-

THE SOLAR SYSTEM AND BACK

30

must have ruined innumerable potential

ings

number

of occasions, though,

markings, he imagined

them

he expected them to be. were missing, he

He

when he

to be the same, since for

poor

felt justified in attributing it to

assumed, very naturally, that

so often, they were there to

astronomers never

make

a

certain

one

thing,

on occasion, the familiar markings

If

meant Mercury faced one

On

sightings.

make out

did

if

he saw

visibility.

particular markings

be seen every time, and that that

side to the

Sun

all

the time.

(I'll

bet

that mistake again.)

This peculiar form of rotation in which the planet presents front to the Sun, then

first its

back,

its

is

astronomers had ever predicted in advance.

not something that

Now

they are busily

engaged in trying to find out what conditions are required to have such a situation

All

I

have

result.

said, so far,

assumes that a planet's rate of rotation

and revolution are constant. This planetary rotation about

its

axis.

invariably true in the case of

is

It

is

not necessarily true for

planetary revolution about the Sun.

For a planet's rate of revolution about the Sun to be constant, its

orbit

circle, its

must be a perfect revolution

Mercury's orbit of

its orbit,

Mercury

at the opposite

is

isn't

end

is

circle. If it is

merely almost a perfect

merely almost constant. even almost a perfect

circle.

At one end

only 28,500,000 miles from the Sun, while

it is

43,500,000 miles from

it.

When

nearest

the Sun, Mercury moves at a speed of 35 miles per second relative to the Sun.

When

farthest away,

it

moves only

at a speed of 23

miles per second. If

Mercury's period of rotation and revolution were exactly equal,

then the inconstancy of

from remaining

While at

its

in

its

one spot

orbital speed

would prevent the Sun

in the sky as seen

closest to the Sun,

from Mercury.

Mercury would be moving

so fast

that y (the Sun's apparent motion due to the planet's revolution) would be considerably greater than x (the Sun's apparent motion due to the planet's rotation). This means that x — y would be a

THE DANCE OF THE SUN negative quantity, and the

Sun would be

31

drifting west to east

(clockwise) across Mercury's sky.

By

the time Mercury was moving toward that part of

that was farthest from the Sun,

its

orbit

so slowly as

behind the rotational period. Then y would be smaller than

to fall x,

would be moving

it



and x

The Sun would

y would be a positive quantity.

drift

west to east (clockwise).

On

the whole, then, the Sun would slide

then

westward,

every 44 days, but maintaining If

first

eastward, then

changing

seem

to

But its

tip, if

mark out

all this is

any,

narrow

a

only

is

direction

average position unchanged.

its

Mercury's axis were somewhat tipped to the Sun

quantity of such

to

westward,

then

eastward,

(and the

not yet certain), the Sun would

ellipse in

Mercury's sky.

Mercury's period of rotation were equal

if

period of revolution, which

it isn't.

The Sun makes

a

com-

plete circuit of Mercury's sky thanks to the planet's nonequal

period of revolution. Imposed upon this

motion produced by the planet's

The

result

is

is

the back-and-forth

orbital eccentricity.

a remarkable dance of the

Sun

science-fiction writer has ever envisaged as far as

I

of a kind

no

know.

Suppose, for instance, you were on a spot on Mercury's surface

which happens

to

have the Sun directly overhead when

at

its

actually at

its

it is

closest.

You

will see the

farthest

from Mercury.

width of the Sun as hot.

Sun

As

it rises

as seen

rise in It

(which

it is

at

its

closest

it

and

the width of the Sun as In fact, the point at

its

is

in the

little

more than twice the

it

grows

largest. It

we

a half times

does slowly, for there are 88 days be-

see

it

By the time it is at zethen more than three times

larger. is

and ten times

on Mercury's surface

largest gets extra

quickly. It

then a

it is

from the Earth and four and

tween sunrise and sunset) nith,

is

the east, while

punishment,

as hot.

directly

for the

under the Sun

Sun does not pass

neighborhood of the zenith that the

ing eastward again. After a while

it

orbital

and sends the Sun movturns and goes westward

velocity overtakes the rotational velocity

7

THE SOLAR SYSTEM AND BACK

32

again, slipping past the zenith

horizon.

As

shrinks until

On

and continuing on

to the western

down through a long, long afternoon, its minimum size again as it sets.

it

slides

it

reaches

it

the directly opposite side of Mercury, the same thing hap-

pens. During one of Mercury's revolutions, one side gets

the next, the other side

does— in

Even more dramatic

it,

during

alternation.

are those places

on Mercury that are 90

removed from the places that get the Sun at zenith at

its largest.

There, the looping motion of the Sun that arises from the nonsteady orbital velocity of Mercury takes place it is

there that the

The Sun more

Sun

is

at

maximum

on the horizon, and

size.

more and

will rise in bloated fashion in the east, rise

slowly, then begin to slip

a second time and this time

it

back and

set.

After a while,

doesn't change

its

mind.

toward the zenith more and more quickly, shrinking as

At

zenith,

It

as

it

it is

down

minimum

to

moves

it

size.

sinks slowly in the west. it is

bloated to

By

the time

full size. It sets,

and

it

Then

it sets

approaches the

after a pause,

again as though to take a last look around and

make

it rises

sure all

is

again for good.

Mercury can thus be divided into four segments, which as to

goes.

sweeps past zenith without turning and begins to grow again

horizon,

well.

it rises

It

whether the Sun

is

high in the sky

when

it is

differ

relatively large

relatively small (Cool Zone). They are arranged Hot Zone, Cool Zone, Hot Zone, Cool Zone. It

(Hot Zone) or alternately:

should be remembered, though, that even the so-called Cool Zone is

super-torrid

What

I

by Earth standards. is the dance of the Sun as seen Hot Zone, then from the middle of

have described

the middle of the

Zone. Other places

differ in

from

the Cool

the exact place in the sky (how high

above the horizon) the large Sun goes through

Nor have we even

first

its

loop-the-loop.

yet exhausted the peculiarities of the rota-

tion/revolution combination. There

turn in the next chapter.

is still

Venus, to which

I will

BACKWARD, TURN BACKWARD

I rarely

take vacations because

occasionally

Some

do.

I

I

hate leaving

years back, the

spent a most successful three-day period in the

peak of the foliage season (and

at the very

New

the foliage turn in

my

typewriter, but

whole family (four of us)

if

White Mountains

you have never seen

England, you have never seen the world

in living color, that's all).

We came down railway (against

from

a trip

my will,

for

up Mount Washington on the cog

am no

I

dare-devil,

but

I

lost the vote

by the narrow margin of three to one) and found that idly getting dark.

My a

wife said, "If

whole I

cluster of

it

we

them

way we came, we

turn back the just a

it

was rap-

to find a motel. will find

couple of miles from here."

with the kind of man-of-the-family decisiveness that

replied,

made

That meant we had

clear there

was

to

be no appeal,

"I

never turn back!

We go

forward!"

And we forest,

did go forward.

We

went forward through

without people or other automobiles.

there were

no

street lights,

and

It

a

state

got pitch dark, for

for twenty-five miles

we went

for-

ward through a universe of blackness, while the children got progressively

more frightened and

I

got progressively more un-

THE SOLAR SYSTEM AND BACK

34

of

all,

we

drove through the most glorious stretch of foliage color in

all

the

easy (what

get a

if I

flat tire

world, and saw none of

On

the whole,

it

here and now!).

Worst

it.

was not one of

my more

intelligent decisions,

something the family nobly forbore saying more than a mere fifty-eight

times during the course of the epic drive.

cuse was a plaintively reiterated, "But

how

could

My

only ex-

we go

back-

ward?" There's something about going the "wrong way" or "backward" that upsets methodical, self-disciplined people like myself, upsets astronomers, too. constitutes frontward

For instance,

if

They have

and backward

you view the

Sun's north pole, then

it

and

distinct notions as to

in motion.

solar system

from high above the

turns out that of the nine major planets

from Mercury to Pluto, exactly nine revolve about the Sun a counterclockwise

it

what

manner

(as

I

explained

in

in

the preceding

chapter).

Therefore, counterclockwise motion

forward motion.

It is "direct

is

the right motion, the

motion." Clockwise motion

is

the

wrong motion, the backward motion. It is "retrograde motion" (from Latin, meaning "backward-stepping").

To be

sure, in order to

judge whether a planet

revolving

is

about the Sun counterclockwise or clockwise, from a position

above the Sun's north pole, the planet's orbit should, in the plane of the Sun's equator. This practice.

The

is

plane of the Earth's orbit

ideally,

be

not exactly so in actual is,

for instance, at

an

angle of 7 to the plane of the Sun's equator. The plane of the orbits of other planets is also tipped to one slight extent or another.

Fortunately, the orbital planes of the various planets are sufficiently close to

one another and to that of the Sun's equator to

enable us to speak of such a thing as a "general planetary orbital plane." This

is

very close to Earth's orbital plane, which

is

usually

referred to as the "ecliptic." I will speak of the "ecliptic" hence-

BACKWARD, TURN BACKWARD— forward as the plane along which the system (the Sun and

The

ecliptic

enough to

its

flat

nine major planets)

lies.

and the plane of the Sun's equator are

raise

no

Difficulties

would indeed

tipped through 180 is still

an equatorial

,

it shifts

orbit,

if

arise if

the plane of a planetary orbit

from an equatorial

but after the

clockwise, not counterclockwise.

the orbital

JL38JL84Q

plane were tipped considerably, however. see in Figure 4,

close

the matter of counterclockwise

difficulties in

and clockwise motion.

As you can

35

structure of the solar

shift,

orbit to

the revolution

Motion has become

is

what is

retrograde.

Figure 4 Orbital Tipping Equatorial orbit direct (counterclockwise)

Equatorial orbit

retrograde (clockwise)

l-EQUATORIAL

VIEW

NORTH POLE

If

the plane of the orbit

is

tipped through an angle of 90

,

it

orbit. Viewed from high above the Sun's north would be seen passing back and forth across the face of the Sun. Its orbit would be seen on edge and its revolu-

becomes a polar pole, the planet

tion If

would be neither counterclockwise nor clockwise. the plane of the orbit, after being flipped 180

motion, were flipped another 180

(360

into clockwise

altogether),

it

would

be equatorial again and back into counterclockwise once more.

THE SOLAR SYSTEM AND BACK

36

In the process, at

it

have gone through another ambiguous stage

will

270 There are a couple of .

"direct"

movement

and "retrograde" what is usually done tip

bad

its

An

for

were referred to only

there would be

were or

how

on astronomy, but it has to the ecliptic would be would be retrograde, and if

in popular writing

orbit that

is

tipped 87

and one that was tipped 93 °

direct this

points.

open to us. We can speak of on one side of the right-angle everything on the other side. This is

alternatives

for everything

as direct or retrograde,

no indication

relatively easy

of

it

how

close the

two

respectively,

cases actually

might be to switch an orbit from

that kind of direct to that kind of retrograde in the course of as-

tronomic evolution.

My own

recommendation would be to drop

and

direct

retro-

grade as far as possible and deal only with orbital tipping.

Any

from o° to 90 and from 270 to 360 would be anything from 90 to 270 would be retrograde.

and

tip

To is

no

be

sure, as far as planetary revolution

fear of confusion.

The

of Pluto, the orbit of which ecliptic,

which certainly

is

concerned, there

greatest orbital tipping is

isn't

in a plane that

enough

is

direct,

is

in the case

tipped 17

to confuse direct

to the

and

retro-

grade.

Nevertheless, there are tions to the solar system,

argument

more than and there

planets and orbital revolu-

will

appear some point to

my

yet.

The unanimity with which

the planets revolve in direct fashion

seems significant to astronomers, and

it

must be explained

theory describing the origin of the solar system.

The

in

any

current

theory has the solar system beginning with a vast cloud of dust

and

gas, rotating

about

that direct motion to

only do the planets rectly

about

Ideally,

by

its

own

all

all

its axis

in direct fashion,

and imparting

the parts that developed out of revolve directly, but the

Sun

it.

Not

rotates di-

axis, too.

this theory, there

should be no retrograde motion

BACKWARD, TURN BACKWARD— anywhere

in the solar system; yet there

motion must be explained,

is.

The

37

cases of retrograde

possible, without seriously affecting

if

the general description of the origin of the solar system.

For instance, comets all

amounts and

a

about the Sun in orbits tipped by

travel

number

of

them

therefore

move about the Sun

in retrograde fashion.

Explanation:

The comets may

very well exist, to begin with, in

a vast cloud spherically arranged about the Sun at a distance of a light-year or

1962).

They

two (see Chapter 8 of Fact and Fancy, Doubleday, represent the fringe of the original cloud of dust

gas, a fringe too rarefied to participate rapidly

enough

and

in the con-

densation of the inner portions and in the centrifugal force that spread the originally spherical cloud into a

quently

when some comets

(possibly

by the

flat

sheet.

Conse-

gravitational influ-

ences of other stars) are sent in toward the solar system proper

from out the vast cometary sphere, they can come in from any direction

and may be retrograde

as easily as direct.

Next come the asteroids. A number of them have highly tipped though actual retrograde motion is not to be found

orbital planes

among them. Explanation:

The

asteroids

may have

originated through an

explosion of a small planet once circling in the region between

Mars and

Jupiter.

The

planet was undoubtedly revolving directly,

but the explosion superimposed a second original

so that

effect

upon

movement. Portions were sent hurling in

some

of the resulting asteroids

And what about

move

that of the

all

directions,

in fairly tilted orbits.

the satellites?

Presumably, the material that was to form the planets con-

densed out of the fringes of the cloud that was forming the solar system, set

up a whirling sub-cloud of

smaller condensations formed in

its

its

own. In some

outskirts to

cases,

become

still

satellites

of the central planet. If this is so, it is to

be expected that the

satellites

would

circle

THE SOLAR SYSTEM AND BACK

38 the planet

or quite near, the plane of the planetary equator

in,

and would do

Of

so directly.

the 32 satellites in the solar system

satellite of

queer combination of circumstances that 5),

no

less

than 20 do indeed

equator. Every 8;

is

less,

to the plane of the planetary

one of these 20 (Mars

and Uranus,

described in Chapter

circle their central planet in orbits

that are tilted by a degree, or

Saturn,

(including Janus, a

Saturn discovered in December of 1966 as a result of a

possesses

Jupiter,

5;

5) does indeed revolve directly about

its

2;

planet.

But what about the other twelve? These do not revolve

in the

plane of the planetary equator and might be termed the "anomalous satellites."

The

best example of an anomalous satellite

for its orbit

angle of

tilt

is

Some

is

our

own Moon,

considerably to our equatorial plane, the

varying from 18.5

Explanation:

Moon

tilted

over an 18.6-year period.

to 28.5

astronomers (and

myself) feel that the

I,

did not form out of the outskirts of the condensing cloud

that was forming the Earth and therefore does not have to circle

Earth in the

latter's equatorial plane.

been independently formed

Rather, the

Moon may

as a second planet in Earth's orbit

and was, eventually "captured" by Earth (see Chapter and Space and Other Things, Doubleday, 1965).

As orbit

7,

Of Time

rather impressive evidence for that, the plane of the is

tilted to

have

the ecliptic by only

5 °. It is

as

Moon's

though there was a

match the Sun's equatorial plane than the Earth's, and this is exactly what is to be expected of a body that was a planet in its own right and a satellite only by later accident. Despite the tilt, the Moon's revolution about the Earth, greater impulse for

it

to

or about the Sun, whichever

way you want

The remaining anomalous Jupiter, 7; Saturn, 2; Jupiter's five

equatorial plane

and

it, is

direct.

satellites are distributed as follows:

and Neptune,

innermost

to view

2.

We

satellites all

can begin with Jupiter.

revolve in the planetary

in orbits that are nearly circular.

Not

so the

BACKWARD, TURN BACKWARD— seven outermost, which are

officially

39

known only by Roman

nu-

merals in the order of discovery. All are small, with diameters ranging from a possible 10 miles to a possible 70. All have orbits that are both markedly tilted to Jupiter's equator

and markedly

eccentric.

They

fall

two groups. Three of

into

VII, and Jupiter

X—all

over 7,000,000 miles.

circle at

(Compare

of Jupiter's five equatorial

them—Jupiter

VI, Jupiter

an average distance of a with

this

satellites,

Callisto, the

which

is

only a

little

outermost over

trifle

1,000,000 miles from the planet.)

The

remaining four—Jupiter VIII, Jupiter IX, Jupiter XI, and

XII—have

Jupiter

orbits at average distances of

to 15,000,000 miles. Jupiter VIII has the

any of the Jovian

satellites.

from 13,000,000

most eccentric orbit of

approaches to within 8,000,000

It

miles of Jupiter and recedes to as far as 20,000,000.

The is

orbital tilt of the inner three of the

about 30

orbital

tilt

anomalous

or so, and their revolutionary motion

of the outer four, however,

(rather close to case

C

in Figure 4)

and

is

satellites

The

direct.

is

something

their orbital

like

160

motion

is

retrograde.

There are two questions. volve in retrograde fashion? into an inner group that

Why And

any do, why

direct

all

is

should any of the

if

this

satellites re-

odd

division

and an outer that

is

all

retrograde?

Explanation: Astronomers are generally agreed that the seven

anomalous Jupiter

is

satellites

of Jupiter are captured asteroids. After

at the outer fringes of the asteroid belt

sional asteroid, passing closely

gravitational field.

The

account for their small ture

would account

by

it,

could be trapped in

its

asteroidal nature of the satellites size

for the

all,

and an occagiant

would

and the random nature of their capmarked tilt and eccentricity of their

orbits. It

can be shown that

asteroid

moving

there are

more

it

is

easier for a planet to capture

an

in retrograde fashion than in direct. Ordinarily,

asteroids

moving

direct than retrograde

and

if

the

THE SOLAR SYSTEM AND BACK

40 approach asteroid,

close

is it

will

enough

to allow the planet to pick

be direct ones that

up any

most probably be captured

will

(like the inner three).

Borderline approaches, however, where Jupiter's gravity just barely counterbalances the Sun's, will not yield a capture unless

the asteroid can

slip into

a retrograde orbit, and that accounts for

the outer four.

If we pass on to Saturn, we find the same situation. Of its ten known satellites, the inner eight are equatorial, and the outer two are anomalous. Whereas the outermost of the eight equatorial

satellites

tenth

(Hyperion)

(Iapetus

is

900,000 miles from Saturn, the ninth and

and Phoebe)

8,000,000 miles from Saturn. dle size, however, with

Phoebe perhaps

The anomalous

about 150

and

and

satellites are of

mid-

800 miles across and

Iapetus perhaps

200.

Again, the inner anomalous Saturn's equator

2,200,000

respectively,

are,

and is

has a

satellite

revolves directly.

The

tilt

of about io° to

outer one has a

tilt

of

clearly retrograde.

Explanation: This would be identical to the one in the case of Jupiter.

That brings us to Neptune's two anomalous.

The

outer one, Nereid,

satellites,

both of them

a small body, perhaps 200

is

miles in diameter. It has an exceedingly eccentric orbit, the most eccentric orbit of any object in the solar system except for various

comets.

The

eccentricity, 0.76, allows

it

to approach

Neptune

to

within 800,000 miles and to recede to a distance of over 6,000,000. Its orbital tilt to

the plane of Neptune's equator

small enough to keep

its

motion indisputably

is

marked but

is

direct.

Explanation: Nereid, too, must be a captured asteroid, though

we might wonder how tune could capture

it

it

managed

in direct

great distance of the Sun,

to get out that far.

motion

is

That Nep-

probably thanks to the

which reduced the competing

solar

BACKWARD, TURN BACKWARD— Even

gravitational pull considerably.

41

the extremely

so,

elliptical

made

probably indicates that Neptune just barely

orbit

the

capture.

And

Neptune's inner

somewhat

larger

satellite,

Triton?

own Moon, and

than our

a large satellite,

It is

it circles

Neptune

in

a nearly circular orbit at the small distance of 220,000 miles

own Moon from

(about the distance of our

own Moon, Could

it

it is

be

not an equatorial our

that, like

Moon, was captured by

but

satellite,

is

%

which seem

satellites,

anomalous.

is

One

larger brother?

its

fact that tends

Moon

that the

is

like

largest of the satellites in terms of the

mass of the planets they Earth, and Triton

our

like

be that Triton,

it

to increase the plausibility of this suggestion

and Triton are the two

And,

Moon, Triton was an independent

planet forming in Neptune's orbit? Could

the

us).

The Moon

circle.

o

%

is

the mass of the

the mass of Neptune. All the equatorial

have been formed as part of the

surely to

planetary system to begin with and could never possibly have

been independent planets, are much smaller in terms of their planets.

But

if

this

orbital plane is.

were

That would

is

would be nice

Moon's

it

not

which

Un-

that touch of the independent planet. so.

The

plane of Triton's orbit

to the ecliptic (and almost as

tune's equator,

to discover that Triton's

least fairly close to the ecliptic, as the

give

fortunately, this

220

so, it

was at

is

much

tipped somewhat

itself

is

tipped

to the plane of

Nep-

to the ecliptic).

This means that Triton revolves in retrograde fashion about Neptune.

Why

should that be?

Explanation:

may have another

The

only one I've ever heard

taken place. Pluto

satellite. Its

is

may once have

that a catastrophe

circled

period would have been 6.7 days

rotational period, see

(its

Chapter 8) and that would place

little

farther out than Triton,

Some

event

may have

Neptune

which has a period of

forced Pluto out of

its

orbit

it

as

present

only a

5.9 days.

and into an

dependent planetary one (of unusually high eccentricity and

intilt

THE SOLAR SYSTEM AND BACK

42

major planet) and the same event

for a

may have

What

tilted Triton's

the event

may

Having done with revolutions about the Sun, how about

rota-

orbit into

present retrograde position.

its

have been, though, no one can suggest.

tions about

an

axis?

I

have already said that the

Sun

rotates

about

axis directly.

its

Ideally, every

body

in the solar system

with their equatorial planes ecliptic.

To

put

it

all

more

ought to do the same,

or less coinciding with the

another way, their axes of rotation ought to be

exactly perpendicular to the ecliptic. This

case of Jupiter, which

has

is

almost true in the

from the

tipped only 3

axis

its

perpendicular.

Our Moon's north lesser extent,

axis

pole

(and of Jupiter about

However, the

is

Moon

is

its

clear data.

We have determined

rotation.

about

its

direct.

is

say nothing of asteroids) are too far

on

Moon

rotation of the

axis)

the only nonplanetary body concerning

we have

the rotation of which

tipped to the ecliptic by an even

and the

only 1.5

The

away

other satellites (to

for

good information

periods of rotation for Mercury

and Pluto but don't have decent data on the orientation of

their

axes of rotation.

What

about the remaining seven planets, however?

mentioned

Jupiter;

and Earth's North Pole,

tipped through an angle of 23.5 ecliptic.

That

is

what

we

as

I've already

know,

all

is

from the perpendicular to the

gives us our seasons,

makes the days and

nights vary in length through the years, accounts for our climatic zones,

and

so on.

However, the

fact that the Earth's rotation

Other planets have Saturn, 27

;

situation here

polar

tilt

rotation

and is

But why

is

not enough to

tilt.

For Mars,

it is

directly,

.

is

that direct motion ceases. For

only tilts

retrograde (see Figure 5). is it

alter the

direct.

a similar polar

All rotate Neptune, 29 the same as for orbital planes. It for

reaches 90 is

is

tilting

that there should be an axial

tilt

at all?

25

;

for

for the

when

the

over 90

,

BACKWARD, TURN BACKWARD— Explanation:

I

know

don't

43

of any official explanation, but a

thought has occurred to me. As the planets form out of the

and

original cloud of gas

large

dust, they

would eventually form

several

chunks which would, for a while, be a "multiple-planet."

Circling in complex orbits they might eventually striking each other off center.

Might

come

together,

not be that the random

it

coming together might end by imparting a bit of "English" to the which would be reflected in the axial tilt?

direction of rotation

Or is this mechanically impossible? Unfortunately, I don't know. And even if this is so, the real surprise is the close correspondFigure

5

Axial Tipping CASEC

ence between the polar

and Neptune. Can

The

90»TIP

25° TIP

0°TIP

this

tilts

180' TIP

of four planets: Earth, Mars, Saturn,

be pure coincidence and nothing more?

planet Uranus has a very odd rotation; for the

Uranus's north pole

is

98 °. This

is

past the 90

mark

tilt

of

so that peo-

ple (even astronomers) usually say that Uranus has a retrograde rotation.

But

it is

call it that. If is

not very retrograde at

you look at Figure

close to that of case

5,

all,

and

it is

misleading to

Uranus's manner of rotation

C. (Jupiter's corresponds roughly to case

and that of Earth, Mars, Saturn, and Neptune, roughly B.)

A

to case

THE SOLAR SYSTEM AND BACK

44

Uranus actually

on

rolls

its side,

direct or clearly retrograde (and

so to speak,

it is

this

I

and

had

is

not clearly

mind when

in

I

argued against indiscriminate use of these terms early in the chapter).

Whatever managed

to

tilt

Uranus's

must have done

axis,

before the planetary system was entirely formed, for the satellites of

circle in

Uranus had

Uranus's

their orbits twisted to correspond

far-tilted equatorial plane.

equatorial satellites of Mars, Jupiter,

so five

and

For that matter, the

and Saturn follow the

tip of

the pole of their planets, too.

Explanation:

I

can only say that off-center collisions produced

a right-angle twist in Uranus's motion. This

weak

suggestion,

I feel,

And now we come known about Venus's

but

to

an extraordinarily

can think of nothing

Venus. Until

recently,

period of rotation or of

One

absolutely nothing.

I

is

else.

nothing was

its

tilt-

axial

simply couldn't see through the clouds,

and the clouds themselves had no markings that could be followed around the planet

There were

as

it

rotated.

guesses, to

be

sure,

and mistaken observations. The

period of Venus's rotation was suggested as anything from 24

hours (like that of the Earth) to 225 days tion). to

its

The consensus was

(its

period of revolu-

that Venus's period of rotation was equal

period of revolution and that, like Mercury,

it

faced one side

forever to the Sun.

But then radar measurements were taken showed that Venus did not face only one

in

1964 and these

any more

side to the Sun,

than Mercury did (see the preceding chapter). Venus's period of rotation turned out to be 243 days, a little longer than period. It

about

its

was the

first

case ever discovered of a

axis in a period longer

its

orbital

body rotating

than that in which

it

revolved

about a central body.

What's more, Venus's north pole was so that

its

case was very

much

tilted at

like that of case

D

an angle of 177 in Figure

5.

,

This

BACKWARD, TURN BACKWARD— meant that Venus's

rotation was retrograde— not fake retrograde,

but

as in the case of Uranus,

we must

Obviously,

real retrograde.

How

ask why.

can Venus, in the process of

Why

formation, have been tipped over completely?

standing on

The

head?

its

45

should

planet-making might account for a 25

final stage of

it

be

notion of off-center collisions in the tilt; it

might

account for a 90 tilt—but a complete 180 tilt? Astronomers are bound to look for something else. Perhaps the

just possibly

effect of

some other body it to take on

as to cause

suspect effect

the Sun, for

is

would

The

1

natural

Venus and

Venus

body

to

gravitational

its

all others.

Venus ought

to have a day that

closely the period of its revolution. If it faces

to the Sun, then

Or

rotation.

close to

it is fairly

swamp

surely

odd

the Sun, though, then

If it is fits

in the solar system so influenced this

Venus-rotation would equal

one

side always

Venus-revolution.

1

there might be something like the case of Mercury where

Mercury-revolution

is

equal to 2 Mercury-days

1

(from noon to

noon). Let's check the length of the Venus-day, then,

from noon to

noon, according to the method described in the preceding chapter.

With

a 243-day rotation about

motion of the Sun is

in the sky of

36o°/243 or 1.48

a negative sign and

Since there daily

is

.

Since the motion

make

is

that

— 1.48

axis,

the apparent daily

as a result of that rotation is

retrograde,

we must have

.

a 225-day revolution about the Sun, the apparent

motion of the Sun

olution

its

Venus

in the sky of

36o°/225 or 1.6

a negative sign so

.

we make

A

Venus

as a result of that rev-

direct revolution

that

— 1.6

must

also involve

.

Adding the two figures, — 1.48 and — 1.6 This means the Sun moves from west to east

,

we have (if it

— 3.08

were east to

west as with us there would have been a positive sign, +3.08 a

little

over 3

noon

)

each Earth-day.

The Sun would make to the next

negative sign

.

still

noon

a complete circuit of Venus's sky, from in 360

/— 3.08

or

—117

days,

where the

stands for a west-to-east motion of the Sun. Con-

THE SOLAR SYSTEM AND BACK

46

we end by

sequently,

saying that

Venus-day

1

equal to 117

is

Earth-days (with the Sun moving in opposite directions in the

two

cases).

This means that the Venus-year

which

not a very even

is

But consider This

this.

The

1.835

is

Venus-days long,

figure.

Venus

synodic period of

584 days long.

is

moments

the period (see Chapter 1) between successive

is

when Venus

is exactly between Earth and the Sun. But then, the synodic period of Venus is almost exactly

Venus-days long. This means that every time Venus

is

5

exactly

between us and the Sun, the same side of Venus, exactly the same side, faces us. It is as

though Venus's period of rotation

But how can that be? an

is

linked

somehow!

to Earth

How

can Earth's puny gravitation have

on Venus that would supersede the Sun's giant

effect

Surely this

is

pull?

impossible?

Explanation: Astronomers are trying to figure this out, but

would

like to

advance

my own

theory.

I

wonder

if

Venus's rota-

tional period has, perhaps, not yet reached equilibrium;

not yet reached a is

slowly speeding

final value.

up under the Sun's influence and

The

tion.

result

Venus-days in

1

its

Its

will,

some

day,

period of rotation will

would then be that there would be

exactly 2

Venus-year. This would be just the case that ex-

on Mercury, except that Venus would do rotation and Mercury by direct rotation. its

has

period of revolution, but in the opposite direc-

ists

As

if it

Perhaps, Venus's rotational period

reach a period of 225 days retrograde.

then be equal to

I

for the apparent connection

it

by retrograde

between Venus's rotation and

synodic period—well, there are coincidences in the universe,

and

think this

I

is

one of them. The thing to do

is

to continue

measuring Venus's rotation as accurately as possible and see there

is

a slow but steady speeding

up

years.

And

if

there is—well, you heard

it

if

of that rotation over the

here

first.

LITTLE LOST SATELLITE

4

The

older one gets, the

This year, as

my

it

more one tends

happens,

celebrate (if that's the

I

thirtieth anniversary as a professional

unbelievable to

me

since

it

to reminisce,

seems to

me

I

suppose.

I

word

I

want)

writer— something quite

am

not very

much more

than thirty years old.

To emphasize right of

this fact, I

an even dozen of

when one

have already had to renew the copy-

my

early science-fiction stories,

begins renewing copyrights,

it

upon the doorstep. So my mind keeps turning back, more than it used first science-fiction story I ever sold— back in October of face it— late youth

is

receipt of the letter of acceptance, with enclosed check,

to, to

1938.

I

couldn't very well frame the check for

I

framed the letter

my

word.

letter.

life.

needed the money, so

letter of acceptance.

modesty

made

intact.

A visitor would

the wall?" and visitor

my

was written with a dead ribbon on gray paper and

only a close scrutiny

kept

I

the

The

from Ray

Palmer of Amazing Stories was one of the high points of

The

and

becomes necessary to

I

I

ask,

it

legible at

all.

This was good, since

it

didn't have to say a single vainglorious

"Why

would merely

have you got an empty frame on say, "It isn't

empty."

Then my

would automatically approach the frame and read the

THE SOLAR SYSTEM AND BACK

48

Best advertisement a modest fellow ever had.

The name

of that

first

story

was "Marooned

never done an essay about Vesta, which I

now ought

So

to.

I will;

generally, for Vesta, as

The

asteroid to

first

No, that

and we

will begin

be discovered was,

would be natural to see the case and I will come back to

it

error.

largest

Vesta."* I've

and

well worth one,

with the asteroids

you undoubtedly know,

not a typographical

is

is

off

an

is

asteroid.

surprisingly, the largest.

You might first,

well suppose that

but that

isn't so in this

it later.

This discovery took place on January

1,

1801, under circum-

Of Time and Space and Other

stances described in Chapter 9 of

Things (Doubleday, 1965), so I won't go into detail here. A second asteroid was discovered in 1802, a third in 1804, and a fourth in 1807,

was

how

and there

it

stopped. For thirty-eight years that

matters stood, and astronomers,

finding four objects in

what was

who had been

rattled at

essentially a single orbit, settled

down.

But you can always count on one troublemaker and it

in this case

was a German astronomer, Karl Ludwig Hencke, who,

decided he would scour the heavens and see fifth.

Year

he found

after

it.

in 1830,

he could find a year he searched and searched and then in 1845

And

in 1847,

he found a

sixth,

if

while the English

as-

tronomer, John Russell Hind, found a seventh and eighth. After that,

it

was

just

Some 1600 had

a rat race.

asteroids are

their orbits plotted,

now

and

sufficiently well

it is

known

to have

estimated that there are about

44,000 asteroids with diameters of more than a mile, and heaven

knows how much rubble less than But never mind the thousands. those

first

a mile in diameter. I

am

going to concentrate on

four asteroids which, between 1807 and 1845, existed

in lonely splendor in

the consciousness of astronomers. Their

names, in the order of discovery

are:

Ceres, Pallas, Juno,

and

Vesta. * Included in

AsimoVs Mysteries (Doubleday, 1968)

if

you are curious.

LITTLE LOST SATELLITE As

figures

I

can find for their diameters are

Table

It

listed in

Table

The

best

1.

1

Asteroids

Diameter ( miles

Ceres Pallas

470 300

Juno Vesta

240

120

seems quite certain that no other known asteroid has a

diameter of as

much

240 miles, so Ceres, Pallas, and Vesta are

as

the three largest asteroids in that order, pretty tion.

49

happens, these are large bodies as asteroids go.

it

A

number of

asteroids,

much beyond

ques-

however, are very likely to have

diameters between 120 and 240 miles and some have actually been estimated (with considerable uncertainty)

to

be

in that range.

However, by virtue of time of discovery and position of

orbit,

Juno makes a natural fourth and we can speak conveniently,

if

not entirely accurately, of the "Big Four."

The Big Four have those of

Mars and

perfectly ordinary orbits, firmly

Jupiter.

Some

Table Asteroids

Eccentricity

(millions of miles)

of Orbit

Juno Vesta

The

closest

farthest

(perihelion)

(aphelion)

237

278

0.079

197 184

319 310

0.258

206

239

0.088

257 257 247 219

Pallas

orbit of Ceres, as

of 0.079

is

less

you

see,

is

2.

2

Distance from the Sun

average

Ceres

between

of the details are given in Table

0.235

nearly circular. Its eccentricity

than that of Mars. What's more,

its

mean

distance,

THE SOLAR SYSTEM AND BACK

5o

257,000,000 miles, all

is

the asteroids whose orbits are known. Vesta's orbit

slightly less circular is.

very nearly that of the average distance of

and

distinctly closer to the

it is

Vesta's farthest point from the

Ceres' closest point.

Four, that

in

is

As

Table

Sun

far

from

it

for the period of revolution of the

only

as

is

Big

3.

Table

3

Period of Revolution

Asteroids

(days)

Pallas

about as

is

is

Sun than Ceres

(years)

Ceres

1680

4.60

Pallas

1686

4.61

Juno Vesta

1593

4.36

1325

3.63

and Juno, from the data given

in

Table

may make

it

sound as

nearly identical orbits. This particularly, are too close

and are going

Not at all. The orbital diagrams you

2,

to collide

seem to have if

these two,

one of these

days.

usually see in astronomy texts are

two-dimensional projections of a three-dimensional are tipped

by

ecliptic), as

different

shown

in

amounts Table

reality.

Orbits

to the plane of Earth's orbit (the

4.

Table 4 Asteroids

Tilt to Ecliptic

(degrees)

Ceres

10.6

Pallas

34.8

Juno Vesta

13.0 7-i

two dimensions, the orbits seem to cross, a threedimensional model would show one crossing far above or far be-

Where,

in

low another. There future.

is

no danger of

collision in the foreseeable

LITTLE LOST SATELLITE

51

customary to consider the asteroids as small

It is

fry

and dismiss

them. Indeed, the most nearly proper name given them by astronomers

"minor planets." But that

is

An

tric classification.

with considerable Saturn, Uranus,

inhabitant of Jupiter might, after

justification,

four planets

just

list

and Neptune) and put everything

Earth on down, into the "minor planet"

So

a purely anthropocen-

is

all,

else,

from

classification.

to consider the Big Four, at least, as objects

let's try

and

(Jupiter,

of individual consideration and see what

we can

worthy about

find out

them.

is

Some have

estimated that the total mass of

about

that of the Earth, or about

%o

only a rough guess, of course, but

let's

This

is

mean

%oo

all

the asteroids

that of the

use

it.

that the total mass of the asteroids would be about 8,500,-

000,000,000,000,000 tons.

The

individual masses of the Big

rough guess) are as shown in Table

(also a

Table Mass

Asteroids

From

5

Per Cent Total

(tons)

Ceres

850,000,000,000,000,000

10.0

Pallas

220,000,000,000,000,000

2.6

Juno Vesta

14,000,000,000,000,000

0.2

110,000,000,000,000,000

1.3

the standpoint of mass, then,

though there

is

only a "Big

second largest

One"— Ceres.

satellite

contains one-tenth of

all

Four

5.

Asteroid

as the

Moon.

This would

it

would

It is

and, within

its

Mass

really

seem

as

four times as massive

own

small sphere,

it

the asteroidal matter. Together, the Big

Four make up one-seventh of

all

the asteroidal matter.

we had reached the Big Four and decided up a base on one of them. What would things be like at such a station? First, how far away would the horizon seem? As it happens, the distance of the horizon from some given low Suppose, next, that

to set

height above the surface

is

proportional to the square root of the

THE SOLAR SYSTEM AND BACK

52

diameter of the planet. Since the diameter of Ceres

Y17

is

just

about

that of the Earth, the distance of the horizon on Ceres would

be about %.i that of the horizon on Earth. If we were standing on the surface of a large

and were of average height

flat

so that our eyes were

plain

5%

on Earth

feet

above

ground, the horizon would be about 16,000 feet away (just over 3 miles)

.

Supposing the Big Four to be smooth spheres, the horizon

distance on

them would be

as

shown

Table

in

6.

Table 6 Distance of Horizon

Asteroids

(feet)

Ceres

4000 3100 2000 2800

Pallas

Juno Vesta

It seems to me this is an important point. The dome of the sky would come down and meet the ground on Ceres, along a circle much closer to your eye than it does on Earth. What's more, on Earth, the presence of an atmosphere dims

objects

on the horizon and turns them

tops of hills and mountains of course, this

and they

mistiness as

When usual,

the air

we

On

is

much

are all the mistier

a

way

very clear

bluish.

(We

can see the

farther than 16,000 feet away,

and bluer

for that.)

of unconsciously estimating

and distant

objects

We use distance.

seem sharper than

automatically think they are closer than they really are.

Ceres, where there

is

no atmosphere, the objects on the

horizon would be sharply outlined. Even the tops of crags farther

than 4000 feet away would be sharp.

We would therefore estimate

the horizon on Ceres to be closer than

me

certain, then, that the

even more so on

men

better

actually

is.

It

seems to

on Ceres (and would be subject to

establishing a base

the other asteroids)

Some, who are used to wide-open might not be able to make it; perhaps the asteroids had

claustrophobic uneasiness. spaces,

it

be

staffed

by

city boys.

LITTLE LOST SATELLITE

53

In another way, the Big Four are not so small after

all.

What

about their surface area?

Table 7 Surface Area

Asteroids

(square miles)

The

Ceres

700,000

Pallas

280,000

Juno Vesta

180,000

45,000

surface area of Ceres

is

just

about

as

large as that of

Alaska plus California. Even the surface area of Juno, the smallest of the four, of

all

four

equal to that of

is

New

York

State,

equal to one-third that of the

is

and the

fifty

total area

United

States.

room to explore on the Big Four and, for that matter, plenty of room to get hopelessly lost in. The question of surface gravity may make the Big Four seem small again. If two spherical bodies are of equal density then the There

is

plenty of

surface gravity

is

proportional to the diameter. If

we assume

that

the Big Four are essentially rocky in character, then they probably have the

the

Moon

same density

as the

Moon. The

(2160 miles in diameter)

In that case,

we can

prepare Table

is

surface gravity of

0.16 that of the Earth.

8.

Table 8 steroids

Surface Gravity (per cent of Earth's)

A

180-Pound Man Will Weigh (pounds)

Ceres

3.5

6.3

Pallas

2.2

4.0

Juno Vesta

0.9

1.6

1.8

3-2

This looks

like a set of feeble grasps indeed. Is it possible that

a person, making a careless move, might shoot upward and away

THE SOLAR SYSTEM AND BACK

54

from the

satellite altogether?

him and would he be it is

Would

the feeble gravity

To

lost in space?

fail

to hold

danger of that,

test the

only necessary to calculate the escape velocity.

Table 9 Escape Velocity

Asteroids

miles/ second ) (

(

miles/ hour )

Ceres

0.33

1200

Pallas

0.2 i

Juno Vesta

0.08

750 300 600

0.16

These values are not high compared to Earth's escape which

is

6.98 miles per second, or 25,000 miles an hour.

velocity,

even

Still

on Juno, the baby of the four, one would have to move at a speed of 300 miles per hour to lift off the asteroid. You are certainly not going to jump upward at that speed. to drive a

by the

asteroid,

seem, will do

But now

and the

its

satellite to

to

is

be the

are not even going

will therefore

gravitational force, small

be held

though

it

may

essential job.*

let's raise

the question of the order of discovery.

at the start of the chapter, that

prising

You

ground vehicle at that speed. You

be discovered was the

it

largest.

that you would expect the brightest,

and the

largest

is

I said,

was surprising that the

The

reason that

first satellite

to

is

first

sur-

be discovered

not necessarily the brightest.

Being large helps, of course. All other things being equal, a large

body catches more sunlight than a small one and

But are

all

other things equal?

matters: distance

Two

factors in particular

is

brighter.

may

affect

and albedo.

was first written, a letter from Thomas McNelly of Corgave me some calculations as to the influence of the centrifugal effect introduced by the possible rotational periods of the asteroids. At the equator, the gravitational pull might be reduced from 5 to 10 per cent, and the escape velocity from 30 to 40 per cent. You would still remain securely on the asteroid but by a narrower margin than I had originally assumed. * Since this article

nell

LITTLE LOST SATELLITE It is clear that

light

catches and the less bright

it

Mars ought

orbit of

55

the farther from the Sun an asteroid

A

it is.

is,

be brighter than a considerably

to

the less

small asteroid near the larger as-

teroid near the orbit of Jupiter,

and the smaller one ought then

be discovered sooner than the

larger.

But

as

it

to

happens, the Big Four are moderately close to us as

asteroid distances go,

and there are no reasonably

are markedly closer than they are. It

is

large ones that

not to be expected then

that any asteroid will be discovered sooner than the Big Four

merely because of a distance difference. Furthermore, the Big Four themselves are not at markedly

enough

different distances; not

any

different, at

rate, to

overcome

the size differential. Eliminate distance, then.

What

about albedo?

Albedo is

is

the fraction of the light, received by a planet, which

then reflected. Thus,

if

a planet reflects one-fifth of the light

from the Sun,

it

has an albedo of 0.2.

receives

As

it

happens, the solid rock of a planetary surface

reflector of light.

and that

is all

exposed to direct sunlight (since there

than *4e of the light 0.06, and the same is true for Mercury.

phere present) albedo

A

is

The Moon, which

has a surface that

reflects less

cloudy atmosphere

is

much

is

is

it

a poor

is all

rock

no atmos-

receives. Its

it

better at reflecting light. Mars,

with a thin atmosphere and an occasional thin cloud, has an albedo of 0.1

5,

two and a half times that of Mercury and the Moon.

Planets with thicker atmospheres reflect an even larger fraction of the light they receive.

The albedo

of the Earth

is

0.40,

while that of the outer planets approaches the 0.50 mark. Venus's clouds do best of

all for

But with respect problem.

It

some

reason,

passes the

bounds of

asteroid should be able to retain asteroids,

generally,

and

its

albedo

is

about 0.70.

to the asteroids, the albedo should raise

as

belief

that even the largest

an atmosphere.

composed of

no

rock,

all

If

we

consider the

should have an

albedo of 0.06. (Indeed, asteroids other than the Big Four have

THE SOLAR SYSTEM AND BACK

56

their diameters calculated

from

known

their

and

distance

bright-

ness by assuming this albedo.)

we can

Therefore, factor.

with

We can

would seem) eliminate the albedo

(it

expect the brightness of the Big Four to decrease

and therefore we can expect that chances are the Big

size,

Four would have been discovered

The apparent magnitude 7 2.5

X

is

in order of size.

brightness of an astronomical

magnitude, which

in

2.5 times as bright as

2.5 or 6.25 times as bright as

we

consider the

first

measured

is

is,

a body of

one of magnitude 8 and

one of magnitude less

and

9,

Table

is

so on.

the brightness.)

three asteroids to be discovered,

works out neatly, as seen in Table

Asteroids

body

That

a logarithmic scale.

is

(Notice that the higher the magnitude, the If

as a

all this

10.

10

Diameter

Magnitude

Brightness

(miles)

(closest to

(]uno

= i)

Year Discovered

Earth) Ceres

470 300

74

3.3

1801

Pallas

8.0

1.9

1802

Juno

120

8.7

1.0

1804

Ceres, the brightest of the three,

be seen by the unaided it,

so

then

you might suppose

which

Pallas,

which

is

is

it

is

too dim, at

its

brightest, to

but even a small telescope only right that

it

was

first

will

show

discovered;

over half as bright as Ceres; and then Juno,

over half as bright as Pallas.

But Vesta it

eye,

is

and should be

larger than Juno,

brighter.

Why was

discovered only in 1807, three years after Juno? It can't be dis-

tance because

it

is

albedo. Perhaps, for

rock and

is

Yet that

even closer than Juno. Perhaps then,

some

reason, Vesta

dimmer than Juno is

is

it

is

composed of darker

despite the larger size of the former.

not so either. In

fact,

being greater than that of Juno,

is

Vesta's magnitude, far from

not only

less

than Juno's but

LITTLE LOST SATELLITE

57

than that of Pallas and even of Ceres. Vesta has a magnitude,

less

which means that

at closest approach, of 6.5,

times as bright as Juno. It

To

put

it

most

is

sharply, Vesta

the brightest of

is

less

than 7.5

the asteroids

all

be made out on a dark, moon-

and

at

less

night by someone with excellent eyes.

its

no

it is

even 2.3 times as bright as Ceres.

brightest can just barely

It is

the only asteroid

that can ever be seen with the unaided eye.

Why,

then, did

take so long to discover Vesta?

it

Ceres was discovered by accident. for

wasn't looking

Its discoverer

any planetary body and he happened to spot Ceres, the second

brightest asteroid. That's reasonable enough.

before they found the

But zling

Why

why Vesta

after

surface area of Vesta

more

light, it

all.

What

is

about

%

just

is

is

should be about

a

%

trifle

means that

The albedo

high.

puz-

it

is

is

Sun and Ceres if the two

actually

must have an albedo that

of Vesta, in fact,

that of Ceres.

closer to the

as bright as

were of equal albedo. The fact that Vesta as Ceres

much more

should be so bright.

Allowing for the fact that Vesta gets

they found Pallas and Juno

is it

much brighter Vesta—years before?

minor mystery,

that's a

is

The

group of astronomers searched

for six years after that, a

Still,

intently for other asteroids.

%

as bright

seven times as

is

possibly as high as 0.5, a

value equal to that of planets with deep, thick atmospheres.

But Vesta

can't have a deep, thick atmosphere.

maining alternative

is

that

it

of ice (or possibly frozen carbon dioxide)

fields

face, reflecting,

The

only

re-

has an icy surface; that there are

on Vesta's

sur-

with considerable efficiency, the feeble light of the

distant Sun.

But

if

that

is

so,

where did the

there be only one asteroid out of

Or

is it

just

asteroids? Is

it

one?

Is it

all

ice

come from?

those thousands that

possible that there are a

just that of

whole

the four, whose diameter

have measured directly with

fair

Why

accuracy, only one

that gives us a false impression of uniqueness?

is

should icy?

class of icy

we happen

is icy,

to

and that

THE SOLAR SYSTEM AND BACK

58

had

All the other asteroids have

on the assumption of

a

determined

their diameters

low albedo. Suppose a number of them

have high albedos and are considerably smaller than we assume. Perhaps an original asteroid-planet exploded,

its

interior form-

its

core,

ing stony asteroids (with a few nickel-irons from

one)

while

surface

ice-encrusted

its

asteroids; with only

Vesta

had

if it

gave birth to Vesta-type

of that type, clearly visible.

itself,

But there are problems. Would the catastrophe leave the ice on Wouldn't the ice be blown off or melted

a surface fragment intact? off

by the energies released by the explosion, and distributed

And would

through space?

the fragment, undoubtedly irregular

now

to begin with, coalesce into the fairly spherical shape Vesta has, with ice remaining

on the surface rather than folding into

the interior?

And

the explosion theory

if

is

eliminated,

what

the alterna-

is

tive?

One

suggestion

asteroid at

all,

to begin with

tion

and

it

is

that Vesta

but a displaced

it

unique, because

is

satellite. If it

would have been a sphere from

might have picked up an

mosphere of the young planet

it

was

ice layer

circling.

it

had been its

is

not an

a satellite

time of forma-

from the outer

at-

Then, somehow, the

satellite

was pulled away from the planet and went wandering

off, lost,

in the asteroid belt.

If s a touching picture of a its

original planet

belt are Jupiter

have been?

little lost satellite,

The

but what would

closest planets to the asteroid

and Mars. Could Vesta have once been a

satellite

of Jupiter?

We

have one piece of information that might help us decide.

In 1967, careful measurements of the brightness of Vesta were

made and

a tiny variation with a period of

Supposedly, this represents of

its

surface

may be

less

its

5%

hours was reported.

period of rotation, for

some

the relatively rocky side shows, the albedo drops and with brightness; as the icy side shows, both go back is

parts

densely covered with ice than others. As

repeated over and over.

up

again;

it

and

the this

LITTLE LOST SATELLITE Such a rotation ought to represent Vesta's revolution about a planet; for

had been

if it

very likely have presented but one face to

a rotation equal to

For a

its

its

59

original period of

a satellite,

period of revolution, like our

satellite to circle Jupiter in

5%

it

would

planet and have had

hours,

it

own Moon.

would have to be

64,000 miles from Jupiter's center, or only 20,000 miles above

cloud layer—much closer than Jupiter's closest present

its visible

satellite.

A

position— even

satellite in that

of

strain

vast

Jupiter's

could withstand the tidal

if it

gravity—couldn't

possibly

have

been

snatched away from that planet's enormous grip by any reasonable

mechanism. Even

away an

some unimaginable catastrophe had ripped from Jupiter, how could it have done

if

inner-satellite-Vesta

so without disturbing Jupiter's other inner satellites?

(How

can

we

the other inner

tell

Well, Jupiter's

five

perfect circles

and almost exactly

plane,

much

circle

Mars

miles above

better.

To

surface. It

Phobos or Deimos and

it

if

Mars, the situation would

5%

hours

would have

it

its

to

center, or 2400

closer to the planet than either

could not have been abstracted from

its

Phobos and Deimos, and those two

Vesta had been abstracted from anywhere by some

cosmic catastrophe, it

have never been

have not been disturbed.

Besides,

but

in almost

their formation.)

4500 miles from

would be

position without disturbing satellites

satellite of

it

the planetary equatorial

in

for satellites that

revolve in

at a distance of its

move about

from the moment of

Vesta were originally a

not be

weren't disturbed?

satellites

satellites

and that can only be true

seriously disturbed If

innermost

it

would very

doesn't, not particularly.

have an eccentric

orbit;

revolves just about

where

likely

And

it

a normal asteroid should. That's asking a lot of coincidence for a little lost satellite.

(On first

the other hand, Richard H.

Weil wrote me

appeared suggesting that Vesta

original

may be

the

after this essay satellite of

the

unexploded asteroid-planet, a most attractive suggestion.

THE SOLAR SYSTEM AND BACK

60

What's more, the well-known So there

is

that very fact, erally,

alas, I

a fascinating mystery about Vesta, it

may have more

and about the

James Blish had missed.)

science-fiction writer

used this hypothesis in a story of his—which,

and because of

to tell us about the asteroids gen-

solar system as a whole, perhaps,

than any

other body between Mars and Jupiter.

When

the time comes, then, that our

out beyond Mars at the port of

first call.

Vesta, please!

last, I

want

manned

spaceships head

to put in a strong suggestion for

B

— THE

OUTER SYSTEM

LITTLE FOUND SATELLITE

5

One week

ago (as

I

write this)

I

visited Brandeis University

a friend to look over a tremendous exhibit of old Bibles

they had on view.

with

which

We stopped at one fifteenth-century Bible, pub-

lished

by Spanish Jews, which was open to the seventh chapter of

Isaiah.

This contained the verse which, in the King James version,

reads in part, "Behold a virgin shall conceive,

The Hebrew word almah, which King James, was not translated ing

at. It

ters,

was merely

is

and bear a son."

translated "virgin" in the

in the Spanish Bible

transliterated

and

left

we were

look-

"almah" in Latin

a fact pointed out in the information card that

let-

accompanied

the exhibit.

My mah sion,

friend

wondered why that was

didn't really

the verse

mean

is

so

and

I

explained that

al-

"virgin." (In the Revised Standard Ver-

translated,

conceive and bear a son.") Yet

"Behold, it

a

young woman

would have been

shall

terribly dan-

gerous for Spanish Jews of that period to translate correctly and

seem

to

be denying the

leaving the

I'm afraid it

virgin birth, so they

evaded the issue by

word untranslated.

my

so often does

enthusiasm caught up with

when

I

am

me

at this point, as

trapped into explaining something.

THE SOLAR SYSTEM AND BACK

64

My

voice reached

oblivious to

my

my own

plain

normal window-rattling pitch and

its

surroundings. What's more,

I

I

grew

went on to

ex-

theories (at considerable length) as to the signifi-

cance of

this chapter of Isaiah and grew eloquent indeed. Finally, what must have seemed an eternity to my friend, I ran down and passed on to other items in the exhibit. The sequel was told me, with obvious delight, by my friend later.

after

It

seems a Pinkerton guard at the exhibit (which was valued

had been

at $5,500,000)

guard said to

my

my

friend,

listening to

I

passed on, the

such an expert?"* and

my name than "Do you know who he is?"

with greater faith in the weight of

friend,

myself have, said, portentously,

The guard thought Oh,

me. After

"What makes him

well, I

a

and

little

I

"God?"

said,

suppose that sort of thing

is

an occupational hazard

and I'm not going to practice my profession though

for the professional explainer

let it rattle

me.

I

I

lower

continue to

will

my

voice next time and, perhaps,

will try to

somewhat subdue

my

gen-

eral air of divine authority.

With

mind known

that in

Saturn was

let's

as

astronomical records. is

Its

take

up the subject of the planet Saturn.

one of the planets from the beginning of

magnitude at

its

brightest

then brighter than any star except Canopus and

easily seen,

even though

it is

ets at their brightest (see

What made

it

dimmer than any

Chapter

is

1).

remarkable, as far as the ancient astronomers

moved more

slowly against the back-

it

ground of the

than did any other planet.

a

fixed stars

complete

it

of the other plan-

were concerned, was that

made

—0.4, and

Sirius, so it is

circle of

The Moon

the sky in a month; the Sun in

1

year;

Jupiter in 12 years. Saturn, however, did not complete a circle of

the sky until 29.5 years had passed. * You may be wondering the same thing. I'm not, really, but I a rather big book about the Bible, the first volume of which was Doubleday in October, 1968, so I'm up on the subject. The title in case you can hardly wait to buy it, is AsimoVs Guide to the I

explain that the

title is

the publisher's and not mine?

have written published by of the book, Bible.

Need

LITTLE FOUND SATELLITE The Greeks

65

movement

interpreted this slow

to

signify that

Saturn was farther from the Earth than was any of the other

known

planets

slowly because fact that

it

to them. In other words,

was so

it

distant.

it

That would

seemed

to

move

so

account for the

also

was dimmer than the other planets.

In this, the Greeks turned out to be correct.

Of

course, they

had no way of knowing the actual distance of Saturn, but, on the average,

it is

about 887,000,000 miles.

It also, as a

matter of

fact,

moves more slowly about the Sun than any of the other visible planets do. Whereas Mercury's average orbital speed is 29.8 miles per second, and Earth's

is

moves

18.5 miles per second, Saturn

along at a mere 6.0 miles per second.

The Greeks

called the planet "Cronos."

ing Cronos are rather unpalatable.

He was

The myths

concern-

the son of Ouranos

(Uranus), the god of the sky, and Gaia (Gaea), the goddess of the earth. His parents had given birth to a series of monsters

whom

Ouranos

in horror

had imprisoned

in hell.

Gaia angrily

encouraged her non-monstrous son, Cronos, to take vengeance.

Armed with

Cronos crept up on

a sharp sickle,

his father

when

the latter was asleep, castrated him, and took over the rule of the universe.

But the crime had dren would serve him

its

as

aftermath. Cronos feared that his chil-

he had served

his father. Therefore, each

time his wife, Rhea, bore a child, Cronos would swallow nally,

when Rhea bore

Fi-

it.

Zeus, she deceived Cronos by giving

him

a stone dressed in swaddling clothes. Zeus was reared in secret,

and when he matured, he warred against Cronos, defeated him,

made him

disgorge his other children,

and then replaced him

as ruler of the universe.

The circles

up

planet

we

call Jupiter

was called Zeus by the Greeks.

the heavens in just under 12 years. Every 20 years,

to the planet Cronos,

so slowly,

it is

fitting to

and passes

name

it

for

an

it.

it

catches

Because Cronos moves

old, old god.

(And

the slow,

heavy motion gives us our word "saturnine.") Because Zeus forever overtaking

and passing

it,

It

the two seem forever to be

is

re-

THE SOLAR SYSTEM AND BACK

66

myth

enacting the old

of Zeus replacing his father

on the

uni-

versal throne.

The Romans

identified their god, Saturn,

an agricultural

with Cronos. (And perhaps they were right to do

may have been an

himself

he used

sickle

myth may

is

which

is

agricultural deity to begin with.

refer, symbolically,

to the harvesting of grain,

where

Cronos with Chronos,

Greek word and which means "time." For that reason,

a

the aged Cronos with his sickle

Time."

The

off.)

a strong tendency to confuse

is

deity,

Cronos

an agricultural implement and the castration

the fertile ears are cut

There

so, for

It is

used to represent "Father

mowing down we pedants

everything

lentless sickle

what time

is

an excellent representation, as

does, but

it

re-

a chilling picture of

is

consider

happens, for the

it

wrong

just the

same.

In July, 1610, the Italian astronomer Galileo Galilei turned his telescope

new

He had

on Saturn.

on the Moon, four stars

already discovered the mountains

on the Sun, and

satellites of Jupiter, spots

everywhere.

What

could he find out about Saturn?

His telescope was, of course, a primitive one, and Saturn was far

away. Galileo couldn't

make out

clearly

but he saw something odd. Saturn wasn't

what

just a

it

round

was he saw, ball, as Jupi-

was a bright something or other on either

ter was; there

side.

Galileo thought they might be a pair of subsidiary bodies, large

twin

satellites,

In 1612, urn,

one on either

when he had

he found the

disappeared.

He

side.

a chance to return to the study of Sat-

satellites

(if

that was

saw nothing but a round

what they were) had ball, like Jupiter,

only

smaller.

Galileo was quite upset. After

new

all,

the telescope was a brand-

instrument, and there were not wanting opponents

insisting that

what

it

made

visible

were merely

who were

illusions, sent

by

the devil to rouse doubt concerning the divinely inspired Biblical

account of the universe.

If

the telescope showed Saturn to be a

LITTLE FOUND SATELLITE body

triple

some times and

at

body

a single

6j

at others, that

would

indeed be a triumph for reaction. Galileo avoided looking at Saturn after that,

"Does Saturn swallow

a friend, asked, petulantly, (I

and

was once asked quite

seriously

in a letter to its

children?"

whether the Greeks might

have been able, somehow, to see Saturn plainly enough to make

and named the planet accordingly. Of course not! The Greeks had no telescope and it is as certain as anything can be this out,

that they never saw Saturn as anything but a point of light.

matter

is

a coincidence,

The

though a particularly interesting one.)

Nearly half a century later the Dutch astronomer Christian

Huygens, with better telescopes at Saturn. In 1655 ne discovered

began to study

his disposal,

had a

it

satellite

and named

it

Titan.

By the next

year,

he had puzzled out what

it

was that had so

make

upset Galileo. His telescope wasn't quite good enough to it

out with indisputable

clarity,

but he, too, could see something

extending out on either side of Saturn. Call

them

a pair of satellites, as Galileo

had done.

If that

were

then they would have to revolve about Saturn. That was a slightly risky deduction, for this was before Newton had advanced his law of universal gravitation which gave a sound theoretical basis for maintaining that a satellite must reso,

volve about

the four

its

planet.

satellites

Still,

If

Moon

revolved about the Earth,

of Jupiter each revolved about Jupiter,

Titan revolved about Saturn. satellites

the

Why

and

not suppose that Saturn's twin

followed the general rule?

these twin satellites revolved about Saturn, their appearance

should alter from night to night. Eventually one should be be-

hind Saturn and one in front so that both would be

Could see

them

this

be what accounted

in 1612?

No! The

invisible.

for the fact that Galileo didn't

visibility

and

invisibility periods

alternate at intervals of a very few days or even hours jects

were twin

The

satellites,

and not

if

should the ob-

at intervals of several years.

only way Huygens could account for the fact that the ap-

THE SOLAR SYSTEM AND BACK

68

pearance of the twin

satellites

remained unaltered

night was to suppose that there were a that there were always

some

some

number

for night after

of satellites so

in front

and back of the planet and

make

the appearance utterly con-

to either side. Indeed, to

ought to be in the form of a ring about the

stant, the satellites

planet.

But then how account

for the fact that the

appearance did

slowly change over the years and that the satellites disappeared utterly

from time to time?

Huygens reasoned that the

ring

might be a thin one which was

tipped to the plane of the ecliptic (to that of Earth's orbit, in other words). This

known

When rings

urn

Saturn

and

is

is

so,

and the angle of

inclination

is

now

to be 26 ° 44'. is

on one

them

see

side of

its orbit,

clearly in front

on the other

and again see them

and

side of the orbit,

we

look

down on

to either side.

we

When

the Sat-

look up on the rings

clearly.

we could watch Saturn every night as it swings from one end of its orbit to the other, we would watch the tipping of the ring begin at maximum-down to maximum-up over a period of 14% If

years as the planet goes

14%

years

goes back to

it

maximum-up

to

(Actually, the

from one end to the other. In another its initial

point and the ring shifts from

maximum-down. tilt

of the rings does not shift. It remains con-

stant with reference to the stars. This constant-tilt-with-referenceto-the-stars

combines with Saturn's motion around the Sun to

produce an apparent Earth. This

is

oscillation-of-tilt

with respect to the Sun, or

not easy to see in the mind alone, so maybe Figure

6 will help.)

Midway between must come

the maximum-up and maximum-down, there when the rings are seen exactly edge-on. The happens midway between the maximum-down and

a time

same thing the maximum-up. This means that every 14% seen edge-on. are not big

If

they are a thin,

flat

enough to magnify the

structure,

years, the rings are

and our telescopes

rings to the point

where the

LITTLE FOUND SATELLITE thickness

is

happened

69

perceptible— they will seem to disappear. That

is

what

to Galileo.

Figure 6 The Tilting of the Rings

SATURN'S ORBIT

Huygens put scrambled the

wanted

his discovery into a

letters

few Latin words and then

by putting them

to preserve priority

in alphabetical order.

if

he turned out to be

right,

reserving the privilege to withdraw without embarrassment

were wrong,

By

an

as did Galileo in

earlier case (see

Chapter

He

while if

he

1).

and he published the

1659, ne was convinced he was right

Latin sentence, which read "Annulo cingitur, tenui piano, nus-

quam

cohaerente, ad ecliptam inclinato." Translated freely,

says that Saturn it

is

anywhere, and

Huygens nothing

is

"surrounded by a thin,

tilted to

flat ring,

it

not touching

the ecliptic."

not to be blamed for his caution. There was simply

like Saturn's ring in the heavens,

It is absolutely

unique among

all

and there

still

the heavenly features

isn't.

we can

see.

What that all?

is

the ring?

It

appears to be a thin,

flat,

solid structure. Is

THE SOLAR SYSTEM AND BACK

70

Huygens's contemporary, the Italian-French astronomer Jean

Dominique

Cassini,

1672, he discovered

is

the next great Saturnian. In

two

1671

(Iapetus and Rhea)

satellites

1684 two more (Dione and Tethys) so that at that time turnian satellites were

And

He

cerning the ring. a third of the

known

he published

in 1675,

way

in

and

and

in

five Sa-

altogether. his contribution to

knowledge con-

detected a dark line curving around

it

from the outer edge. Huygens thought

about it

was

a dark marking

on a solid ring. Cassini thought it was a separaand that there were really two rings, one outside the other. The outer one we can call Ring A and the inner Ring B.

tion

Cassini turned out to be right, and the dark marking he dis-

covered

is still

As a matter of fact there none are so broad and easy to

called "Cassini's division."

are other divisions, too, though see as Cassini's.

Anyway, since 1675, we speak of the "rings" of

Saturn, not the "ring."

New

continued to turn up. In 1789, the German-

satellites

English astronomer William Herschel discovered a sixth and sev-

enth

satellite

(Mimas and Enceladus). He

rotation of Saturn

by following spots on

Saturn rotated in

10%

hours and that

pendicular to the plane of the rings. circle

Saturn along the line of

its

its

its

also

surface.

studied

He

axis of rotation

The The

the

found that

was

per-

rings, in other words,

equator.

inner satellites also

revolve exactly in the plane of Saturn's equator.

The

rings cast a

shadow on the planet they

to suppose they are solid

and continuous.

A

circle so it

is

easy

strong point in favor

came with the work of the American astronomer William Cranch Bond. In 1848, Bond detected an eighth satellite of Saturn (Hyperion). He made the discovery on September 16; the English as-

of an alternate possibility, however,

tronomer, William Lassell, independently 18.

Two

days

is

Next, in 1849,

two days— Bond

Bond and

made

it

on September

gets the credit.

his son,

George Philips Bond, observed

that the rings of Saturn extended closer to the planet than had

LITTLE FOUND SATELLITE

71

been reported. There was an innermost ring that was dimmer than the

their report

C)

So much

The

certainly couldn't

on November

on December that, too,

and through which

rest

part (Ring

3

and

lost

stars

could be seen. That

be continuous. The Bonds made

15. Lassell

made an independent

report

out again, poor fellow. (See Figure

for observation.

pointed to rings

There was theory,

made up

in addition,

7.)

and

of discontinuous particles.

rings spread out widely in space

and were under the

Figure 7 Saturn as Seen from Above

influ-

One Pole CASSINI'S DIVISION

ence of a gravitational

field

The innermost boundary

that varied in intensity with distance.

of the ring system

is

only 44,000 miles

THE SOLAR SYSTEM AND BACK

72

from Saturn's center (and only 7000 miles above Saturn's surface), while the outermost boundary

86,000 miles from the center

is

of the planet.

We

know

Newton worked

Saturn's mass.

from the distance of

its satellites

and

out

it

first

1687

in

their period of revolution,

using his law of universal gravitation, and his figure has had to

be corrected only

slightly since.

Saturn has 95 times the mass of easily that the gravi-

Earth and from that we can calculate quite

boundary of the

tational intensity at the innermost

and

at the outermost

boundary

0.2

tensity at the surface of the Earth

is

rings

is

0.8

(where the gravitational

in-

taken as 1.0).

In other words, the outermost regions of the ring are under only a quarter the gravitational intensity of the innermost

re-

gions. This gives rise to a strong tidal effect that puts a strain

on

the rings inward and outward.

Then,

most

too,

under the lash of the gravitational

sections should

in their revolution

should

move

move

at a velocity of

12%

force, the inner-

miles per second

about Saturn, while the outermost sections

at 10 miles per second. If the rings

were

solid,

they

would have to move in one piece with the innermost sections going more slowly than the outermost. This would put a tremendous sideways strain on the system. In 1857, the Scottish mathematician James Clerk Maxwell a thoroughgoing analysis of the gravitational situation

that the rings could not stand the strain

uously solid unless they were

They had

many

if

made

and showed

they were contin-

times as rigid as the best

steel.

to consist of separate fragments so thickly strewn as

to appear continuous

when viewed from the

distance of Earth

(not so thickly strewn in Ring C).

This has been borne out amply since.

James Edward tions

The American astronomer

showed by spectroscopic observathat the inner portion of the rings did move more quickly Keeler, in 1895,

than the outer.

As

know how

we

still

don't

telescopes improved

and

as the rings

Despite everything, though, rings are.

still

thick the

remained

LITTLE FOUND SATELLITE invisible

when

several

At

first,

hundred miles

thick, then less

maximum

seen edge-on, the estimates of

ness decreased.

was

it

they had to be

felt

then

thick,

less

than ten miles thick.

73

must be measured in yards some estimates to the effect that they

than

than several dozen miles

Now

thickness

thick-

less

it is

generally felt their

at the most.

I

have seen

are only a foot thick.

The size of the individual particles in the ring is also not known. The thinner the rings, the smaller the particles might be expected to be. They may be no larger than so much gravel. From the efficiency with which they reflect light and from their infrared spectra, it

seems the gravel may be coated with

ice,

or even be mainly

ice.

But why should Saturn have

rings at all?

No

other planets

have them. Well, in 1849, before Maxwell's definitive analysis, a French astronomer, E. Roche, that

when

a satellite

tidal forces will

made and

more general approach and showed primary are of the same density,

a

its

break up the

satellite if it

is

closer to the planet's

center than 2.44 times the planet's radius. This

is

called Roche's

limit.*

There are

six

planets

known

to have satellites. If

we omit

Sat-

urn, here are the figures for the distance of Roche's limit for each

planet and the distance of

its

nearest satellite:

Table Planet

11

Roche's Limit miles

Nearest Satellite

radii

miles

radii

Earth

9,750

2.44

238,500

Mars

5,150

2.44

5,800

2.74

Jupiter

105,000

2.44

110,000

2.56

Uranus

37,000

2.44

77,000

Neptune

35,500

2.44

220,000

60.0

5.17 15.1

* Actually, Roche calculated it on the assumption the satellite is fluid and has no tensile strength. Actual solid satellites can withstand tidal forces better than that and if a satellite is small enough it can remain unbroken even quite close to a planet.

THE SOLAR SYSTEM AND BACK

74

For every one of these planets, the

system

satellite

outside

is

Roche's limit although, in the case of Mars and Jupiter, the

nermost

For Saturn, the distance of Roche's limit

most known is

satellite, as

is

88,500.

The

inner-

December, 1967, was Mimas, which

of

120,000 miles from Saturn's center (3.44 radii). Saturn's

lite

in-

satellite is interestingly close to that limit.

system

is

The outermost edge

of the rings

is,

on the other hand, 86,000

miles from Saturn's center, or 2.38 radii. therefore,

The

inside Roche's limit. Either

is

satel-

also safe.

it

entire ring system,

represents a satellite

which somehow managed to get too close to Satum and which broke up, or

represents part of the original cloud of matter

it

about Saturn which was too close to Saturn for allow If

it

to coalesce into a satellite in the

the rings are a disintegrated

rather large one.

mass of the inal satellite

I

satellite,

tidal effects to

place.

first it

may have been

have seen one estimate which placed the

Moon.

rings at one-quarter that of the

would have had

If so,

a

total

the orig-

to have a diameter of about 1300

miles.

And what about the division (which

Cassini's division? If there is

were

particles in

about 2500 miles wide, by the way), they

would revolve about Saturn

in 11 hours.

However, Mimas revolves

and Tethys in 45 hours. would be pulled by Mimas from the same direction every two of the particle's revolutions, by Enceladus every three, and by Tethys every four. The same pull from in 22 hours, Enceladus in 33 hours,

A particle

in Cassini's division

the same direction would permanently slow closer to Saturn, or speed

until the

new

distance

is

it

up and

force

it

it

down and

farther

force

such that the synchronization

stroyed. In this way, Cassini's gap

is

swept clear of

it

from Saturn is

de-

particles.

Other gaps are likewise swept by synchronization with the nearer satellites, but nowhere is the sweeping as multiple and as efficient as in Cassini's division.

But now

let's

consider Saturn's

satellites.

In 1898, the Amer-

LITTLE FOUND SATELLITE ican astronomer

ninth

urn's

75

William Henry Pickering discovered Phoebe,

satellite,

and

nothing new was added.

The

Sat-

almost seventy years after that,

for

list

of

satellites,

from Saturn out-

Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion, Iapetus, and Phoebe. It almost seemed as if that were

ward,

was:

going to be permanent.

To

be

named

sure, Pickering reported a tenth satellite in

it

He

Themis.

reported

from Saturn, which placed

Two

satellites so

spaced.

Of

1905 and

at a distance of 908,000 miles

at nearly the orbit of Hyperion.

near the primary are not likely to be so closely

course,

Themis was reported

and a rather high

of 39

it

it

to

have a high inclination

eccentricity as well, so that

it

wasn't likely

However, a high inclination and

to collide with Hyperion.

ec-

centricity for a satellite that close to Saturn are also unlikely. It

a suspicious satellite all

is

that

around and

Themis was never seen

taken, that's

A

it is

again. Pickering

not at

all

surprising

must have been mis-

all.

close study of faint divisions in Saturn's rings, however, in-

dicated that additional satellites, very close to Saturn, might exist. If so,

be

they would be so close to the outer edge of the rings as to

lost in their glare.

Then,

December, 1967, something

in

dra-

matic happened. This was a time when Saturn's rings showed edge-on and disappeared, and such a once-in-fifteen-year opportunity can

be important. With the

rings out of sight, objects in the

near vicinity of the rings might be seen. In that December, a French astronomer, Audouin Doll f us,

lo-

cated a tenth satellite of Saturn, closer to the planet than Mimas, even.

The

little

found

satellite

proved to be 98,000 miles from

the planet's center (2.73 radii), which puts

than Mimas, but

still

it

22,000 miles closer

10,000 safe miles outside Roche's limit

and 12,000 miles beyond the outer edge of the satellite revolves

Dollfus

named

it

Janus after a

Roman god who

The new

is

pictured with

and one backward. Janus is beginnings and endings, of arrivals and departures, of

a double face, one looking forward

the god of

rings.

about Saturn in 18 hours.

THE SOLAR SYSTEM AND BACK

j6 entrances and

of doors in

exits,

and doors out (which

is

why

the

guardian of the doors, and, eventually, of the house generally, called a "janitor"). In this case, the

discovered and the so

it is

the largest

how

is

satellite

new

satellite is

the

be

last to

reading from Saturn outward,

estimated at 300 miles, which would

would

make

it

discovered in over a hundred years. Consider-

surely

you can

have been discovered long ago

if it

see

hadn't

for the rings.

Janus's invisibility

seeming to swallow it

list

telescopes have improved in that interval,

that Janus

been

on the

"Janus."

Janus's diameter

ing

first

is

disgorge.

is

its

another case of Saturn (and of children. Dollfus

its

rings)

was the Zeus that made

6

VIEW FROM AMALTHEA

months ago

Several

2001:

A

ment

I

I

attended a preview of the motion picture

Space Odyssey here

in Boston. Against

my

better judg-

even got into a tuxedo for the occasion.

Perhaps the tuxedo contributed to an unwitting bit of pomposity

my

on

irrational

part,

for at

one point

I

dissolved into a

semi-

spasm of anger.

see, I have included in a number of my stories something "The Three Laws of Robotics," of which the first is: "A robot may not harm a human being or, by inaction, allow a human being to come to harm." The laws are a purely fictional device, but they had been picked up by other writers, who take them for granted in their robot stories, and over the years I have come to take them very seriously indeed.

You

I call

In 20oi the most dramatic episodes involve an intelligent comf

my

puter (equivalent to one of

about the death of several

robots)

human

happen was made abundantly

beings.

who

the aisle toward a friend of mine

Law! They're breaking

I

First

this

was going to

clear to the audience just before the

mid-point intermission, and at intermission

In tones of deep shock,

deliberately brings

That

I

said to

Law!"

I

went seething up

noticed in the audience.

him, "They're breaking First

THE SOLAR SYSTEM AND BACK

78

And my

friend answered, calmly, "So

why

them

don't you strike

with lightning, Isaac!"

Somehow

my

that restored

perspective

and

watched the

I

rest

of the picture with something like calm and was even able to enjoy

an arousal of

curiosity.

Near the end of the picture when the spaceship was approaching Jupiter, several satellites were visible as small globes near the giant globe of the planet

itself.

at once, trying to figure out

them

all in

I

started counting the satellites

whether

it

was

really possible to see

the sizes indicated from any one point in space.

Unfortunately, because they kept changing scenes, and because I

could not remember the necessary data exactly enough or manip-

ulate

them without trigonometric

tables,

I

could

come

to

no

conclusion.

So

let's

To

you and

I

work

out together now,

it

begin with, Jupiter has twelve

known

if

we

can.

of which

satellites,

four are giants with diameters in the thousands of miles, and the

other eight are dwarfs with diameters of a hundred

fifty

miles or

less.

Naturally,

want

we want

if

to choose

giants. If

we

do, then seven of the eight dwarfs are

millions of miles

than

we would

to see a spectacular display,

an observation post reasonably close to the four

away and would not be seen

as

bound

to

be

anything more

starlike points of light at best.

Let's ignore the dwarfs then.

There may be some

following a starlike object that shifts stars,

but that

is

not at

all

its

position

comparable to a

interest in

among

the other

satellite that

shows a

visible disk.

Concentrating on the four giant that or

we

more

satellites,

we

will surely agree

don't want to take up an observation post from which one

much of its time in the direcwe would be forced to watch it defy anyone to pay much attention

of the satellites will spend

tion of Jupiter. If that happens,

with Jupiter in the sky, and

I

VIEW FROM AMALTHEA to

any

when

satellite

there

is

79

a close-up view of Jupiter in the field

of vision.

For that reason, we would want our observation post in a

posi-

tion closer to Jupiter than are the orbits of any of the four giant

Then we can watch

satellites.

all

them with our back

four of

to

Jupiter.

We

could build a space station designed to circle Jupiter at

and always watch from the side away from Jupiter, but bother? There is a perfect natural station with just the prop-

close range

why

erties

we

need.

It is Jupiter's

The

innermost

any of the

closer to the planet than

satellite, a

four giant satellites of Jupiter were the

discovered anywhere in the solar system

Moon, 1610,

dwarf that

first satellites

(except for our

to

Galileo,

be

own

Three of them were discovered on January and he spotted the fourth on January 13.

of course).

by

is

giants.

7,

Those remained the only four known satellites of Jupiter for And then, on September 9, 1892, the American astronomer Edward Emerson Barnard detected a fifth one, much dimmer and therefore smaller than the giant four, and nearly three hundred years.

also considerably closer to Jupiter.

The cal

discovery

came

as

somewhat of

having four ently, that

proper

satellites

and no more. The shock was

of

its

own. They called

Jupiter's satellites to

come

so great, appar-

astronomers could not bear to give the newcomer a

name

the discoverer, and also "Jupiter

has

a shock, for the astronomi-

world had grown very accustomed to thinking of Jupiter as

to

V"

it

"Barnard's Satellite" after

because

be called Amalthea,

after the

was the

it

be discovered. In recent

years,

nymph

fifth

however,

(or goat)

of it

who

served as wet-nurse for the infant Zeus (Jupiter).

Amalthea's exact diameter

is

uncertain (as

every satellite in the solar system but the figure given

is

is

Moon

the diameter of

itself).

100 miles with a question mark after

it. I

The

usual

have seen

estimates as large as 150 miles. For our purposes, fortunately, the

exact size doesn't matter.

THE SOLAR SYSTEM AND BACK

80

There

is

no

direct evidence,

but

it

seems reasonable to suppose

that Amalthea revolves about Jupiter with one face turned eternally toward the planet. Jupiter's mid-point

is

edge of that "sub-Jovian"

The

horizon.

When

the center of Jupiter

side,

satellite,

standing on the very

planet (as seen from Amalthea)

isphere before

Jupiter

half the surface of the

is

is

right

on the how-

so huge,

one must go a considerable distance into the other hem-

ever, that

From

On

always visible.

all

of Jupiter sinks below the horizon.

roughly one-quarter of the surface of Amalthea, eternally

is

of

all

below the horizon and the night sky can be

contemplated in peace and quiet. For our purposes, since we want

we

to study the satellites of Jupiter,

will

take a position

(in

imagination) at the very center of this "contra-Jovian" side of

Amalthea.

One

object that will be visible in the contra-Jovian

Amalthea, every so often,

n

Jupiter in

will

be the Sun. Amalthea revolves about

hours and 50 minutes. That

too, with respect to the stars

is its

sky in 11 hours

will

period of rotation,

and (with a correction too small to

worry about) with respect to the Sun as well.

Amalthea, the Sun

sky of

make

appear to

To an

observer on

a complete circle of the

and 50 minutes.

Since Amalthea revolves about Jupiter directly, or counterclock-

Sun

wise, the

and there

With

am

will

appear to

will

be

5

rise in

the east and set in the west,

hours and 55 minutes from sunrise to sunset.

this statement,

which

I

introduce only to assure you

not unaware of the existence of the Sun,

matter of

satellites exclusively for

Sun has something I will

take

The

up

to

will pass

on

I

to the

the remainder of the essay.

The

do with them, but what that something

is,

in the next chapter.

four giant satellites, reading outward from Jupiter, are: Io,

Europa, Ganymede, and Jupiter

I

I,

Jupiter

II,

in abbreviated form,

Callisto.

J-I, J-II,

Sometimes they are

and Jupiter IV J-III, and J-IV.

Jupiter III,

called

respectively or,

VIEW FROM AMALTHEA

what we want, the abbreviations are very conven-

Actually, for

The names

ient.

mind which

we go

centrate

are irrelevant after

nearer and which

is

With

by.

all,

and

farther

is

and

difficult to

it is

that's

what we need

to

keep in

those names are

if

we can

the abbreviations, on the other hand,

on the order of distances of the

vious way,

8l

all

con-

satellites in a very ob-

make the

data in this article

meaningful.

Using the same system,

can and, on occasion,

I

will

call

Amalthea J-V. Generally, though, since it is to be our observation point and therefore a very special place, I will use its name. So

let's start

satellites

with the basic

statistics

Table 12), with those

(see

good measure. Of the data

for

for Callisto as high as

you in

is

Amalthea 12,

For instance, can

I

tell

little

have seen

I

What

I

figures

have given

from the various sources

library.

For comparison, the diameter of our own so that

also included

the least satisfactory

3220 and as low as 2900.

the consensus, as far as

my

Table

in

are the values for the diameters.

concerning the four giant

for

we can

thinner,

say that

and

J-III

J-I is

a

little

Moon

2160 miles,

is

wider than our Moon,

J-II

a

and J-IV considerably wider.

In terms of volume, the disparity in size between

on the one hand, and our Moon, on the other, the two largest Jovian satellites

is

3.3

is

J-III

and J-IV, Each of

larger.

times as voluminous as the

Moon. However, they are apparently less dense than the Moon (perhaps there is more ice mixed with the rocks and less metal) so that they are not proportionately more massive. Nevertheless, J-III

massive as the

Moon;

is

massive enough.

it is

It is

not only twice as

the most massive satellite in the solar

system. For the record, here are the figures on mass for the seven giant satellites of the solar system (see Table 13).

cludes not only the four Jovian giants and our

can

call E-I),

therefore N-I, will

but Triton, which

and Titan, which

be made clear

later.

is I

The

Moon

Neptune's inner

will call

S-VI

table in-

(which

satellite

we and

for reasons that

THE SOLAR SYSTEM AND BACK

82 If

we

are going to view the satellites, not from Jupiter's center

(the point of reference for the figures on distance given in Table

Table 12-The Five Inner Jovian Satellites

Name

Satellite

Diameter (miles)

Distance from

Center

Jupiter's

(miles)

J-v

Amalthea

J-I

Io

100

113,000

2,300

262,000 417,000

J-II

Europa

i,95o

J-III

Ganymede

3,200

666,000

J-IV

Callisto

3,200

1,170,000

Table 13-Masses of Satellites

Name

Satellite

Mass (Moon =

J-III

Ganymede

2.1

S-VI N-I

Titan

19

Triton

i-9

J-IV

Callisto

i-3

EI

Moon

1.0

JI

Io

1.0

J-II

Europa

0.65

12) but from the observation post

1.0)

on the contra-Jovian surface of

Amalthea, then we have to take some complications into account.

When

any of the

satellites, say J-I, is directly

contra-Jovian point,

it

and Amalthea form a

above Amalthea's straight line with

Jupiter. J-Fs distance

from Amalthea

from

minus the distance of Amalthea from

Jupiter's center

ter's center.

This represents the

is

then equal to

minimum

its

distance of

distance

J-I

Jupi-

from

Amalthea.

As

J-I

draws away from

from the observation point

when

it is

this

overhead position,

increases,

and

is

its

distance

considerably higher

on the horizon. The distance continues

to increase as

VIEW FROM AMALTHEA it

sinks

below the horizon until

83

reaches a point exactly

it

opposite side of Jupiter from Amalthea.

The

entire

on the

width of

Amalthea's orbit would have to be added to the distance between

Amalthea and

Of

J-I.

from our vantage point on Amalthea's surface, we would only be able to follow the other satellites to the horizon. course,

We will be faced with a mum

minimum

distance at either horizon.

details,

I

distance at zenith and a maxi-

Without

will present those distances in

troubling you with the

Table

14.

Table 14-Distances of the Jovian Satellites from Amalthea Distance from Amalthea (miles)

Satellite

At zenith

At horizon

J-I

149,000

236,000

J-II

304,000

403,000

J-III

553,000

659,000

J-IV

1,057,000

1,168,000

This change in distance from zenith to horizon peculiar to Jupiter's satellites. It

observation

Moon

is

is

is

not something

true whenever the point of

not at the center of the

orbit.

The

distance of the

from a given point on the surface of the Earth

is

greater

when the Moon is at the horizon than when it is at the zenith. The average distance of the center of the Moon from a point on Earth's surface is 234,400 miles when the Moon is at zenith and 238,400 when it is at the horizon. This difference is very small because

it is

When

the

only the 4000-mile radius of the Earth that

Moon

is

is

involved.

we must look at it across half which we need not do when it is at the

at the horizon,

the thickness of the Earth, zenith.

From

a point

on Amalthea's

surface, however,

we must

across a considerable part of the 113,000-mile radius of

which makes more of In the case of our

look

its orbit,

a difference.

Moon, we

are dealing with an orbit that

is

THE SOLAR SYSTEM AND BACK

84

markedly

elliptical so that

one point

in its orbit

and

it

can be as close as 221,500 miles at

as far as 252,700 at another point. For-

tunately for myself and this discussion, the orbits of the five

Jovian satellites

and

we

ellipticity is a

are discussing are all almost perfectly circular

complication

Given the distance of each diameter of each

don't have to face here.

satellite

satellite, it is

size of each, as seen

we

from Amalthea, and the

possible to calculate the apparent

from our Amalthean viewpoint (see Table

15).

Table 15-Apparent Size of Jovian Satellites as Seen from Amalthea Diameter (minutes of arc)

Satellite

At zenith

At horizon

J-II

53 23

34 17

J-III

20

17

J-IV

10

9

J-I

If

you want to compare

this

with something familiar, consider

that the average apparent diameter of the

This means that

J-I,

for instance,

is

Moon

is

just slightly larger

Moon when it rises, bloats out to a circle half again as Moon when it reaches zenith, and shrinks back to size

when

it

sets.

The

other three

31' of arc.

satellites,

than the

wide its

as the

original

being farther from

Amalthea, do not show such large percentage differences in distance from horizon to zenith

and therefore do not show such

differences in apparent size either.

Notice that although

J-III is

also considerably larger.

from Amalthea so that from the other

considerably farther than

The two

J-II

and

effects

J-III

counterbalance as seen

appear indistinguishable one

in size, at least at the horizon.

closer, bloats just a little

more when

J-II, it is

it

Of

course, J-II, being

reaches zenith.

As

for J-IV,

VIEW FROM AMALTHEA smallest in appearance,

it is

diameter of our

The

85

and shows only one-third the apparent

Moon.

sky of Amalthea puts on quite a display, then. There are

four satellites with visible disks, of which one

But never mind

satellite,

Sun, and (its

considerably

what about brightness? Here

size;

factors are involved. First there

each

is

Moon.

larger than our

is

several

the apparent surface area of

then the amount of light received by

from the

it

by

finally the fraction of received sunlight reflected

albedo). In Table 16,

I list

it

each of these bits of data for each

of the four satellites, using the value for our

own Moon

as basis

for comparison.

Table 16-The Jovian Satellites and Our Moon atellite

Apparent Area

Sunlight

(Moon =:i.0)

Received

Maximum Minimum (Moon=

Albedo

(Moon =

H

2.92

1.20

0.037

j-ii

0.55

0.30

0.037

5-5

j-iii

0.42

0.30

0.037

3

J-IV

0.10

O.O84

0.037

0.4

If

we

consider the figures in Table 16,

from Amalthea

is

ceives,

however

that received by the after

Sun

all,

as

is

at

it is

Moon. This

J-I

as seen

up

is

of sunlight

satellites),

not surprising.

is

it re-

only

%

The Moon,

an average distance of 93,000,000 miles from the

compared

The Moon

see that

At zenith it our Moon. The intensity

do the other Jovian

(as

we

5

will possess an area

remarkable.

to three times that of

1.0)

1.0)

to 483,000,000 miles for the Jovian satellites.

has no atmosphere and therefore no clouds— and

atmospheric clouds that contribute most to light reflection.

The Moon,

therefore,

the light

receives

it

showing bare rock,

reflects

only about

from the Sun, absorbing the

rest.

%4

of

THE SOLAR SYSTEM AND BACK

86

The Moon's mark

is

%

bettered by

and

J-II,

J-I,

which

In fact,

J-III.

J-II reflects

about

good

Earth can manage. This doesn't necessarily mean that

as the

of the light

these three satellites have an

Earth.

seems more

It

it

receives,

is

every bit as

atmosphere and clouds

like

the

likely that there are drifts of water-ice

and

ammonia-ice (or both) on the surfaces of the

satellites,

and that

these drifts do the reflecting. Callisto, for

and

some

reason, reflects only

%

oi the light

composed

is

that astronomers have badly overestimated (If

it

Or

of particularly dark rock.

were smaller than astronomers think

is it

conceivable

Callisto's

it is,

receives

Moon. Perhaps

therefore less than half as reflective as the

is

Callisto

it

it

diameter?

would have

to

more light to account for its brightness.) Anyway, we can now calculate the apparent brightness of each

reflect

satellite

(as

compared with our Moon) by multiplying the area

by the amount of sunlight received by the albedo. The

results are

given in Table 17.

Table 17-Apparent Brightness of the Jovian Satellites Apparent Brightness (Moon

Satellite

= i.o)

Maximum Minimum

As you thea, can

J-I

0.54

0.22

J-II

0.11

0.06

J-III

0.045

0.033

J-IV

0.0015

0.0012

see,

not one of the Jovian

compare

from the Earth's

in

tieth;

J-II

is

less

and J-IV

And

yet

who

is

Even

J-I,

Moon

as seen

the closest to Amalthea and

never better than half as bright as the

than a seventh

less

seen from Amal-

apparent brightness with our

surface.

therefore the brightest,

Moon;

satellites, as

as bright; J-III less

than a twen-

than a six-hundredth.

says brightness

is

everything?

only %65>ooo as bright as the Sun, and alone, it is all the better for that.

if

Our own Moon is we consider beauty

VIEW FROM AMALTHEA Perhaps the Jovian

more

seen from Amalthea will be

Moon,

beautiful than our

It will result,

will

satellites as

87 still

for being so softly illuminated.

perhaps, in better contrast, so that craters and maria

be more clearly

visible. If

the

satellites are partly ice-covered,

patches of comparative brilliance will stand out against the darkness of bare rock. It will be

all

the more startling because on Amal-

thea there will be no air to soften or blur the sharpness of the view.

may be most

Callisto

beautiful of

field glass to see it at its best. It

mysteriously low albedo. Perhaps

its

lump

of coal, with

ice so interspersed

diamonds

its

There are only two

it

may

might look rather

than a solid

it

will

seem

a cluster of

ten.

Uranus

is

so

in a way.

Whereas no

less

it still

tackle

for Jupiter.

From

and

puts on a bet-

than seven of Jupiter's twelve

small and distant they can be ignored,

Saturn's need be neglected.

let's

satellites to Jupiter's twelve,

only one giant as compared to Jupiter's four,

show

real

a special problem

briefly in

Although Saturn has only ten

ter

have

opposed to merely one or two. These are

and Saturn with

Chapter 3), but Saturn according to the system we have already used

are

with

like a

circle of light.

planets, other than Jupiter, that

mentioned

(for reasons I

require a

satellite,

very occasional patches of highly-reflecting

families of satellites, as five

it

by very dark rock that

in the sky, rather

Uranus with

though

all,

would be a darkling

only three of

Saturn's innermost satellite, six

other satellites can be seen with visible disks, and not four only. Let's satellites

start

(see

by giving the basic

The Roman numerals for Jupiter satellites

for

statistics

Saturnian

the

Table 18).

but

I

are not as well established for Saturn as

have seen them used from

I

through IX for the

from Mimas through Phoebe. Janus was discovered

at

won't

re-

the very end of 1967 (see the preceding chapter) but

I

organize the numbering system because of that. Just as Jupiter's closest satellite

is

S-X (even though

J-V, so it

I

will let Saturn's closest satellite

looks like a prudish

way

be

of writing "sex").

.

the solar system and back

88

Table 18-The Saturnian Satellites

Name

Satellite

Diameter

Distance from Saturn's Center (miles)

(miles)

S-X

Janus

300

98,000

SI

Mimas

320

115,000

S-II

Enceladus Tethys

370 800

149,000

Dione Rhea

800

234,500

1,100

328,000

S-VI S-VII

Titan

3,100

760,000

Hyperion

250

922,000

S-VIII

Iapetus

2,213,000

S-IX

Phoebe

750 190

S-III

S-IV

s-v

Besides,

if

we

8,043,000

place our observation point on Janus (or S-X)

will

be convenient to number the

and

so on.

we assume

If

183,000

satellites in its

sky as

S-I, S-II,

that Janus presents one face, always, to Saturn

and take up our position

at the contra-Saturnian position,

never see Saturn and

rings

on the

We

nian

its

and we

will

we

will

be able to concentrate

satellites.

can work out the zenith and horizon distances of each

satellite

system,

it

from Janus,

as

we

did in connection with the Jovian

and from that determine the apparent

satellites (see

As you

see,

most three

sizes of

the Satur-

Table 19).

the situation on Janus

is

most amazing. The

are only starlike points

satellites

omitted from the table.

The

other

six

outer-

and are therefore

satellites,

which are

in-

cluded, are so closely spaced and increase in size so steadily as one

goes outward that

the same

our

size.

own Moon

all

appear, on the horizon, to be very

much

All have an apparent diameter about half that of (S-I

a little smaller, while

and

S-III are a little larger, S-II

S-IV and S-VI are

This picture of sextuplet

satellites

and S-V

are

just right) is

quite unique. Nothing

view from amalthea Table 19-Apparent

from Janus

as Seen

Diameter (minutes of arc) Zenith Horizon

Satellite

like it

89

Size of Saturnian Satellites

SI

65

S-II

25

11

S-III

32

18

S-IV S-V S-VI

20

15

17 16

13

18

15

can be seen from any other point in the solar system, not

even from any other point in the Saturnian system.

Each effect

of the six satellites bloats as

approaches the zenith, the

it

being more extreme the closer the

from a diameter half that of the

Moon

of the

Moon

at zenith. Its area

satellite.

S-I

expands

at the horizon to twice that

(and therefore

any given phase) increases thirteen-fold, as

it

its

brightness at

travels

from horizon

to zenith.

And

the brightness of the Saturnian satellites? Here there

difficulty that

for there are

turnian

was not present

no

We

I

However,

S-I

can find on the albedos of the Sa-

and

S-II are

thought to be largely

is

the solar system

albedo of the Saturnian

satellites 0.5, or

seven times that of the

Moon. Working with

that assumption and realizing that the

delivers only 0.011 as

much

our

own Moon, we can

Saturnian

satellites as

about as bright

Sun

light to the Saturnian satellites as to

calculate the apparent brightnesses of the

seen from Janus (see Table 20).

Here we have a picture of ellites,

a

known to have an atmosphere (the only satelknown to have one). won't be too far out then if we decide to make the general

snow and S-VI lite in

figures that

satellites.

is

in the case of the Jovian satellites,

a soft

and

as Callisto (the

delicate family of

dimmest

dim

sat-

of Jupiter's four

giant satellites), as seen from Amalthea. All are only

%

o to

%

o

THE SOLAR SYSTEM AND BACK

90

Moon. Only one

as bright as the

to shoot

Does Jupiter

So

of the Saturnians, SI,

up to the unusual mark of

%

as bright as the

this give us all we need to know about the and Saturn? Heavens, no!

far

I

have painted only a

and

static picture

fascinating aspects of the situation untouched. lites

of Jupiter as seen from Amalthea,

manages

Moon.

satellites of

left

the most

Those four

and those

satel-

six satellites

of

Saturn as seen from Janus, are moving relative to each other. Each

moves

at

its

own

characteristic rate

and the group forms an

ever-

changing pattern.

What's more, the Sun moves mentioned

briefly

across the sky, too (something I

near the beginning of the chapter) and that

introduces interesting complications, too, such as phase-changes

and I

eclipses.

will try to

work out the motion picture of the Jovian

lites, at least, in

satel-

the next chapter.

Table 20-Apparent Brightness of Saturnian Satellites Satellite

Brightness

(Moon =

Zenith

Horizon 0.0032

S-I

0.0115

S-II

0.0042

0.0020

S-III

0.0057

0.0032

S-IV

0.0035

0.0027

S-V

0.0030

0.0023

S-VI

0.0028

0.0027

1.0)

THE DANCE OF THE SATELLITES

People always seem to be amazed over the fact that

I

am

forever

writing about spaceships but never get into an airplane; that

my

have

characters travel

all

over the galaxy while

I

I

myself drive

to a neighboring state only with the greatest reluctance.

"You don't know what

And to

they're right,

be said

you're missing/' they keep saying.

suppose, except that there's something also

I

thought alone.

for traveling in

three-dimensional as the real thing, but

For instance, about

and the

Falls,

trip

borhood of the cinated;

it

We got a

Falls,

I I

Falls

had

and

my

was so pleased

lay

down

pulled into the neigh-

I

it

was!

I

was

fas-

had nerved myself

at last, so that

My eyes closed,

a train that neither

was.

I

clear

dull roar that filled the

it

We

to

I

might sink

so richly earned.

tried to.

frown rested on

where

drove the family to Niagara

I

turned a corner, and there I

quite as

nice pair of rooms in a motel in the very near neigh-

into the rest

was

may not be

saves trouble.

trip.

borhood of the at least

ago

wasn't bad at that.

was majestic;

the 400-mile

Or

five years

It

it

then opened, and a puzzled

and ingenuous forehead. There was a

room

like a

nearby train except that

it

approached nor receded, but remained

THE SOLAR SYSTEM AND BACK

92

After a while,

identified the sound.

I

With

great indignation

I

realized that they did not turn the Falls off at night.

There you have

it.

An

sive as the real thing,

imagined Niagara

but

may not be

quieter.

it is

never see the view from Amalthea which

I shall

the previous chapter— not even

if

tem were

moment

available at this very

as impres-

described in

I

a rocket ship to the Jovian sys-

with tickets for sale at a

and one of them reserved in my name. Still, I can imagine the view, and do so, gratis, in the peace and quiet of dollar a passenger

my

attic.

While I'm

at

it,

then,

satellites of Jupiter as

will

I

now go on

moving

to consider the five inner

bodies, rather than as static ones.

All revolve about Jupiter in fixed periods.

The

closer to Jupiter,

the faster a satellite moves relative to the planet and the smaller its

orbit about

We

it;

and, for both reasons,

its

period

is

shorter.

can begin then by considering the period of revolution of

each of the

satellites

comparable,

we can

and, in order to give

them

all in

make

those periods directly

hours (see Table 21).

In traveling a circular path about Jupiter, each satellite sweeps (since every circle, whatever

over 360

360

By

).

Table

its size,

can be divided into

dividing the period, in hours, into 360

we

,

find

21 -Motion of Jovian Satellites Relative to Jupiter

Name

itellite

Period

Motion per Hour

(hours)

(degrees of arc)

J-V

Amalthea

11.83

J-I

Io

42.45

J-II

Europa

86.22

J-III

Ganymede

171.7

J-IV

Callisto

400.5

+30.43

+ + + +

8.50 4.18 2.10

0.90

many

degrees of arc each satellite traverses in one hour.

figure

is

The

how

given in the last

column

That

of Table 21.

degrees of arc traversed in an hour are given as positive

THE DANCE OF THE SATELLITES figures,

because the

moving

satellites are

in

direct,

Chapter 3). Suppose we imagine ourselves somewhere above

93 or counter-

clockwise, rotation (see

tor, well

above

can observe the

its

Jupiter's equa-

unimaginably stormy atmosphere, so that we comfort. Suppose, also, that

satellites in

motionless with respect to Jupiter's center, which means

not partake in Jupiter's rotation. All the

satellites

we are we do

would then be

seen to rise in the west, travel across the sky, pass overhead, then sink in the east.

But suppose we

ourselves, while observing,

iter in

the same counterclockwise direction.

slowly,

we would

seem

partially overtake

to us, then, to

move more

the west and set in the

and

east,

the

slowly.

were to

circle Jup-

Even

we

satellites

if

did so

which would

They would

rise in

still

but would take longer between

rising

setting.

we speeded our own motion more and more, the satellites would seem to move more and more slowly, as observed by ourselves from our moving vantage point. Finally, if we circled JupIf

iter at a

speed that swept out +0.90 ° per hour,

even with Callisto.

The

east,

motionless in the sky as

we matched

could

still tell

stay

rise in

but Callisto would seem to remain

the west and set in the

we

we would

other satellites would continue to

that Callisto was

it

step for step.

(Of course,

moving by comparing

its

posi-

tion night after night with the neighboring fixed stars, but in this essay

we

are completely ignoring the motion of the satellites

relative to the stars.

system

Our view

is

confined entirely to the Jovian

itself.)

If we continued to hasten our motion, we would more than match Callisto— we would outrace it and it would seem to fall behind. It would rise in the east and set in the west and would seem thus to travel in a direction opposite to that of its real mo-

tion relative to Jupiter.

(No

mystery!

If

two

trains

were racing in

the same direction on parallel tracks, passengers on the faster train

would

see the slower train

overtaken, even though

it is

seem to move backward

really

moving forward.)

as

it

is

THE SOLAR SYSTEM AND BACK

94

As our own personal speed increased, we would next overtake Ganymede and force that into apparent east-to-west motion, then Europa, then

But

Io,

and

so on.

not set ourselves an arbitrary motion. Let us place our-

let's

selves

on Amalthea, J-V, where we were

That

will give us a fixed

interested in a

more

about Jupiter

something

is

Jupiter's center,

and

in the preceding chapter.

speed of +30.43 ° per hour. (If you're figure,

Amalthea's speed

like 16.7 miles per

second relative to

easily

this

is

visualized

nearly equal to the 18.5 miles-per-

second figure of Earth's motion about the Sun. Compare this

with Callisto, which moves at a speed of only

5.1

miles per second

relative to Jupiter's center.)

Amalthea sweeps out many more degrees any other of takes

them

and so

Jupiter's satellites, of course,

all.

of Amalthea,

From

all

in the west. (I

it

time than

handily over-

our vantage point on the contra-Jovian side

the giant satellites would

am

in a given

rise in

the east and set

assuming, here, that Amalthea turns one face

eternally toward Jupiter.)

We

can easily determine the rapidity of this motion relative to

Amalthea by subtracting the degrees-per-hour motion of Amalthea relative to Jupiter from the corresponding value for each of

the other four

hour

satellites.

relative to Jupiter

Thus,

and

to Jupiter, then Callisto

if

Amalthea moves +30.43 ° per

Callisto

moves +0.90 per hour

relative

— 29.53



moves (+0.90) (+30.43), or The minus sign here would

per hour relative to Amalthea.

indi-

cate that Callisto, as seen from Amalthea, was traveling east to west.

The motions

of the various satellites as seen from

Amalthea are

given in Table 22. Having presented the names of the satellites in

Table

21,

1

will

henceforward (as

I

did in the previous chapter)

continue to refer to them only by the

Roman

numeral

identi-

fication.

As you west,

see,

the

satellites all

something which

reflects

move

quite rapidly from east to

Amalthea's very rapid motion

the dance of the satellites

95

Table 22-Motion of Jovian Satellites Relative to Amalthea

Motion per Hour

Satellite

(degrees of arc)

-21.93 -26.25

J-I

J-II

J-III

-28.33

J-IV

-29.53

The

from west to

east.

that satellite

moves and the more

after

Amalthea. None of the

course, but

only 22

Amalthea, the

closer a satellite to

effectively

satellites

it

does this very well, of

the closest to Amalthea, manages to

J-I,

faster

tends to chase

per hour, whereas J-IV, the most distant,

fall

behind

falls

behind

29 y2 ° per hour. It

thea, it

would seem then that the more distant

and the more slowly

moves

we

it

in Amalthea's sky.

a satellite

turns about Jupiter, the

This

may sound

from Amal-

more quickly

paradoxical, but

all

more distant and slow a satellite, the more rapidly it is overtaken by Amalthea. Let's put this into more familiar terms. From the motion in are saying

that the

is

degrees per hour,

would take to

it is

through a complete to

Amalthea

not hard to calculate

traverse

(see

360

circle

.

and

This would give

its

how many move the

Table 23-Period of Jovian Satellites Relative to Amalthea Period of Revolution (hours)

J-I

16.4

J-II

13-7

J-III

12.7

J-IV

12.2

it

satellite

period, in hours, relative

Table 23).

Satellite

hours

THE SOLAR SYSTEM AND BACK

96

The rise

period of revolution gives us the time lapse from

Amalthea

satellite-

(Actually, there's a small complication here

to satellite-rise.

somewhat over a hundred thousand miles removed from the center about which the satellites orbit. This means that a given satellite is 226,000 miles farther from Amal-

in that

is

thea at some parts of seen from Amalthea satellite-rise to

its

satellite-set

strictly is

as

uniform and the time from

not quite equal to the time from

We

satellite-set to satellite-rise again.

com-

will dispose of these

by ignoring them.)

plications

It so

motion

orbit than at other parts. Its

not

is

happens that Amalthea and the four giants

all

revolve in

orbits that are nearly exactly in Jupiter's equatorial plane. Callisto's

orbit

(Compare

is

the most tilted but even so

this

about 18

only about

is

own Moon, which

with our

has an

off.

orbit tilted

to the plane of the Earth's equator.)

This means that every time one

Amalthea's

sky, there

Ganymede and

is

an

Callisto to just miss

another in

passes

satellite

(Actually,

eclipse.

it

one another

times, but even for them, a partial eclipse

is

possible for

in passing,

would be the

In order to determine the frequency of eclipses then, necessary to calculate

how

long

would take one

it

take another. It would always be the

would do the overtaking

more



for

it

rapid east- to-west motion.

is

more

some-

rule.) it is

only

satellite to over-

distant satellite that

the more distant that has the

The more

distant satellite

would

approach the nearer (and usually larger-in-appearance) from the east, slip

behind

it,

There would be

The

six

at

its

west.

types of two-satellite eclipses altogether.

period between such eclipses, and the

would take from Table I

and emerge

initial

maximum

time each

contact to final break-free, are given in

24.

leave

it

to

you

to calculate

(if

you wish) the time between

the various possible three-satellite eclipses: I-II-IV, I-III-IV, and II-III-IV.

You might wonder why

I've left

out

I-II-III,

but apparently the

the dance of the satellites Table 24-Satellite-Eclipses

Time between

Eclipse

97

Seen from Amalthea

as

Maximum

Eclipses

Duration of

(hours)

Eclipse (minutes)

J-IV/J-III

300

25.0

J-III/J-II

173 110

20.7

/J-I

83

17.5

J-III/J-I

56

11.7

J-IV/J-I

47

8.2

J

IV /J-II

J-II

three innermost giant satellites,

10.1

J-I, J-II,

and

J-III,

do not move

completely independently in their orbits but maintain a certain fixed relationship that precludes their ever being in a straight line

on the same line

side of Jupiter (although they can

be

in a straight

with two on one side of Jupiter and one on the other).

This eliminates the

what would have been

I-II-III eclipse

a

and

also

(more's the pity)

most remarkable coming together of

all

four satellites in Amalthea's sky.

But now, what about the Sun? Amalthea sume) one

on

its

rotates about Jupiter in side always facing Jupiter.

axis, relative to

11.83 hours, with

That means

it

(we

as-

also rotates

the Sun, in 11.83 hours. (The correction

that needs to be applied as a result of Jupiter's motion in

its

about the Sun in the course of that 11.83-hour period

so small

it

is

orbit

can be ignored.) As seen from Amalthea's contra-Jovian point,

then, the there

is

Sun

rises in

the east at 11.83-hour intervals, so that

a 5.92-hour day

and a 5.92-hour

night.

(The changing

distance of Amalthea from the

Sun in the course of the satellite's revolution about Jupiter is small enough to be neglected.) To a viewer on Amalthea, the Sun would be just 6' of arc in

diameter, a bit less than one-fifth Earth. This means that the

its

diameter as seen from the

Sun would be

just visible as a distinct

globe, rather like a glowing pea in the sky.

THE SOLAR SYSTEM AND BACK

98 Its its

apparent area,

as seen

%7

as bright.

The

Y27

from Amalthea, would be only

apparent area as seen from Earth and

it

of

would therefore be only

brightness would be entirely due to

fall-off in

the smaller apparent area of the Sun and not in the least due to

the lesser brightness of the Sun

Sun

itself,

area for area.

The

pea-sized

Amalthea would be just as bright as a similar-sized section of our own Sun would appear to be if the rest of it were blocked of

off. I

would suggest then that our Amalthea-based viewer would

not find

it

comfortable to stare at the Sun, shrunken though

it

might appear. Amalthea's shrunken brightest object in

To show

its

that, let's

Sun would

be the incomparably

still

sky.

abandon Amalthea's contra-Jovian point for the other hemisphere, where we can see Jup-

a while

and move

iter. If

the Sun were on the other side of the

to

be shining over Amalthea's shoulder,

up the

and

to speak,

so

We

entire visible face of Jupiter.

would

satellite, it

lighting

would be seeing

"full-

Jupiter."

Jupiter

would then be

quarter the

full

a shining glory,

width of the

43 ° across, or nearly one-

would be —20.2

sky. Its brightness

magnitude, or 1100 times as bright as our

full

Moon

seen from

Earth's surface.

The

Sun, however, for

all its

—23.1 and would be 14 times

shrunkenness, has a magnitude of

as bright as Jupiter at its brightest.

What's more, when the Sun and

Jupiter are both visible

Amalthea's surface, Jupiter must be in that

it is

even

less

considerably

dimmer than

less

it is

than

its

from

half-phase, so

and

at the full

is

then

able to compete with the diamond-hard brilliance of the

tiny Sun.

Now

let's

get back to our contra-Jovian point,

where Jupiter

is

never visible and where the Sun can only be compared to the satellites.

The comparison

is

pathetic, in that case.

brightest of the satellites (as seen from

than about half as bright as our

about 32,000 times as bright

full

Amalthea)

Even is

Io,

the

never more

Moon. Amalthea's Sun

as Io at its brightest.

is

THE DANCE OF THE SATELLITES when

Furthermore, all

the Sun

is

in

99

Amalthea's contra-Jovian

sky,

the satellites that are above the horizon are in the half-phase

and are correspondingly dimmer. They are merely washed-

or less

out crescents.

As the Sun swoops east to west,

than Callisto.

from

across Amalthea's contra-Jovian sky

does so faster than any of the

it

The Sun moves

at a rate of

even

satellites, faster

— 30.43 °

per hour (an

exact reflection of Amalthea's motion about Jupiter, as you can see in

Table 21).

The Sun shown

in

therefore overtakes each

Table

25. If

see that the length of time lar satellite is

of the four satellites,

you compare Table 25 and Table it

takes the

Sun

equal to the length of time

it

21,

you

as

will

to overtake a particu-

takes that satellite to

the Sun once.

circle

during the period from solar overtaking to solar overtak-

It is

ing that each satellite goes through

and back

to full

to new.

The

period

its is

remains longest in Amalthea's sky. In the case of

from crescent at satellites

J-I,

which it

J-I,

rising to nearly "half-Io" at setting.

change phase

from new

cycle of phases shortest for

also

can go

The

other

less spectacularly.

Table 25-The Sun and Satellites from Amalthea

Time between Satellite J-I

J-II

Solar Overtakings (hours)

42.45 86.22

J-III

171.7

J-IV

400.5

The Sun is farther from Amalthea than are any of the satellites, when the Sun overtakes a satellite, it can pass behind it

so that

and be

eclipsed.

This would happen every time

if

the Sun's ap-

parent orbit were in the same plane as the orbits of the

However,

all

satellites.

the satellites revolve in Jupiter's equatorial plane

THE SOLAR SYSTEM AND BACK

100

which

to the plane of Jupiter's orbit about the

tipped 3

is itself

Sun. That means that the Sun's path across Amalthea's sky

from the points of intersection there

90

the Sun's path and those of the

in-

such a way that at places

tersects the paths of the satellites in

will

be

gap between

a 3

This

satellites.

big enough to

is

allow the Sun to miss the satellite completely so that there will be

no

eclipse.

However, every once

be only

slightly separated

they are not separated at

How

and an

all)

stance, the

size of the

9'

of arc.

The

between the Sun and Callisto must be

make

pear to

I

2'

am

contact.

of arc

if

The

Callisto

not enough of a

of 6'

satellite

satellite.

of arc,

7.5' if their

to eclipse the

celestial

must

For

in-

and J-IV,

distance, center to center,

edges are to ap-

distance, center to center,

is

calculations precisely, but I

Sun and

Sun and

Sun has an apparent diameter one of

point of intersection

eclipse will then take place.

close to the point of intersection

at the horizon,

will overtake a particu-

(at the actual

be depends on the apparent

than

Sun

in a while, the

the point of intersection that the two will

lar satellite so close to

Sun

must be

less

entirely.

mechanic to make the appropriate

by making some rough estimates (and

hope I'm not too badly

off)

I

have worked out the data

presented in Table 26.

Table 26-Satellite Eclipses of the Sun Satellite

Number of

of Total Eclipses

Time between Total

Sun per Hundred

Eclipses (hours)

Overtakings J-I

8

530

J-II

4

2,100

J-III

3%

J-IV

1

On

5,200

40,000

the average, then, there will be one solar eclipse of

every 400 hours.

The chances

of seeing the

Sun

some sort by one

eclipsed

THE DANCE OF THE SATELLITES satellite or

Such an

another on any given Amalthean day

eclipse

is

101

about

in 66.

1

more common than on Earth and more

is

viewed, too, because the

satellites'

shadows cut across

easily

of small

all

Amalthea, whereas the Moon's shadow narrows down to almost nothing by the time solar eclipse

The

reaches Earth's surface so that any given

it

can be viewed from only a terribly restricted area.

total eclipse doesn't last very long,

motion of the Sun

when J-IV

in Amalthea's sky

utes under the last scrap

Callisto

so rapid. It endures longest

the eclipsing body, since J-IV has the largest ap-

is

parent motion of any of the

the

is

because the apparent

would take

satellites. It

fully 5

min-

most favorable conditions, between the time when

Sun disappeared behind

of the eastern edge of the

and the

scrap of the western edge reappeared

first

other side. For the other

satellites,

the eclipse never

on the

lasts

more

than 2 to 4 minutes.

A

solar eclipse

Earth, in

and

it

not as spectacular on Amalthea as

is

some ways. The Sun's corona

would be hidden by the

satellite.

from Earth

solar eclipse as seen

coincidence that the

is

dimmer than

it it is

is

on

here

(The impressiveness of

rests largely in

a

the extraordinary

Moon and the Sun have almost equal apMoon just fits over the body of the Sun,

parent sizes so that the allowing Still,

points.

show lites

all

the corona to be visible.)

solar eclipses,

as

seen from Amalthea, will have their

As the Sun approaches one of the

as a thin

and shrinking

are in the sky, farther

crescent. If

satellites,

the latter will

one or two other

removed from the Sun, they

satel-

will

be

rather thicker crescents.

As the Sun disappears behind the one satellite, the other one or two would stand out brightly against a sky which now lacked the brightness of the small Sun.

What's more, there would be another phenomenon, ably

more

that— a phenomenon which will take While the Sun is high in Amalthea's contrais nearly full on the other side of Amalthea.

interesting than

a bit of explaining.

Jovian sky, Jupiter

consider-

THE SOLAR SYSTEM AND BACK

102

(When

the Sun

is

at zenith over the contra-Jovian point, Jupiter

is

entirely full.)

This means that the Jupiter-light shining on the the Amalthean sky

is

satellites in

considerable. Ordinarily, a viewer at the

contra-Jovian point on Amalthea would not be aware of Jupiterlight.

During the Amalthean nighttime, the Sun would be on the

other side of the

the

near Jupiter, and Jupiter would be a

satellite,

would be comparatively dim, delivering

crescent. It

satellites in

the contra-Jovian sky.

On

little light

the other hand,

to

when

the Sun was high in the sky and Jupiter was fat and bright on the other side of Amalthea, what light the planet delivered would

be dimmed by comparison with the Sun's

brilliance.

But what about the moment of solar eclipse, when Jupiter is bright indeed and the Sun is suddenly not there to compete. The satellite

behind which the Sun

Amalthea

lit

%

best, only

by

would be

is still

at

its

very

rather impressive.

satellite,

under the circumstances.

that satellite would be black

invisible against the black, airless sky except as a

blot against the Sun. it

side-towardis,

(from the Amalthean view-

particularly impressive

As the Sun passed behind a by contrast and

its

sure, Jupiter-light

4 as bright as sunlight

point) but that It

hidden, has

is

To be

Jupiter-light.

But then, when the Sun disappeared behind would seem to flame out— suddenly

altogether, the satellite

visible in Jupiter-light.

Other

satellites in

as crescents

the sky at the time would

still

by sunlight but the remainder of

facing surface would be

lit

by

be marked out

their

Jupiter-light and, with the

momentarily absent from the

sky,

Amalthea-

Sun

itself

that Jupiter-light would be

more clearly visible. Under favorable conditions, our own crescent Moon has the rest of its body very dimly lit by earthlight ("the old Moon in the new Moon's arms") but it must be remembered that Jupiter-light is

considerably brighter than earthlight under comparable condi-

tions.

And

would be

in addition, the sunlit portions of the Jovian satellites

less brilliant

than the sunlit portions of our Moon.

THE DANCE OF THE SATELLITES So

and

far I

have described two types of

IO3

eclipses, satellite-satellite

satellite-Sun. Let's consider a third type.

Imagine the Sun to be

circling

about Amalthea

observer on Amalthea's surface) and

on the hemisphere facing

let's

by an

(as seen

imagine ourselves to be

Jupiter.

Each time the Sun makes its circle, it must pass behind Jupiter's swollen globe and would spend 1.4 hours behind it, too, so that there would be an eclipse for nearly one-quarter of the daylight

Nor would

period, during every daylight period.

there be any

Jupiter-light bathing Amalthea's surface, for during the period of

the eclipse, Jupiter would be in

its

"new" phase, presenting only

dark side to Amalthea.

its

On

Jupiter's contra-Jovian side,

such an eclipse would never be

directly seen, because Jupiter itself

the

Sun

is

is

never directly seen.

in the contra-Jovian sky there

is

no chance

When for

an

momentary ones by the satellites). The contra- Jovian side of Amalthea gets the full 5.92 hours' worth of sunlight— one-third more than the Jupiter-side gets. However, the eclipse of the Sun by Jupiter can be detected indirectly, for Jupiter's shadow falls on any of the satellites that may be on the night side of the planet. eclipse (except the occasional

From Amalthea's

contra-Jovian side,

it

will

be

possible, at in-

tervals, to see one satellite or another move into the Jovian shadow and blink out. Nor will it be lit by Jupiter-light, for, of course, it will be facing Jupiter's night side and the huge planet

will I

his

be in the "new-Jupiter" phase. suppose an observer on Amalthea's contra-Jovian

knowledge of the Sun and the

and from

would be able its size

side,

from

which he could

see,

manner in which each satellite on occasion when the Sun was not in the sky,

his observations of the

would be eclipsed of

satellites,

just

to

deduce the existence of Jupiter and get an idea

from those

eclipses,

even

Amalthea's other side to see for himself.

if

he never traveled to

THE PLANETARY ECCENTRIC

8

Some months

my wife and

ago,

very funny one-act plays.

We

I

saw Plaza Suite,

a trilogy of three

enjoyed them hugely in themselves,

and we enjoyed them the more because the two leads were such favorites of ours and so good. There are very few people who are not just a little star-struck,

my wife has a feeling hidden deep within her that me as a tool with which to meet those few certain

of course, and

she can use

stars that strike her.

science-fiction fan, self

.

.

if

that

I

all,

I

she reasons,

if

one of them

is

a

walk boldly up and introduce my-

.

The one what

After

and

catch

is

refuse to lend myself to this. After

all,

they are not science-fiction fans? Think of the humilia-

if

tion!

So

I left

the theater, holding her elbow firmly and ignoring her

plaintive plea that

magic name.

We

I

make my way backstage and announce my

went

to the restaurant next door instead for a

cup of coffee while she glared daggers at me.

And

waitress told us in great excitement that the entire

then the

company

of

Plaza Suite was in that same restaurant.

Can I said,

I

fight Fate?

I

sighed and removed

resignedly, "Til

chance

it."

my

napkin. "All right,"

THE PLANETARY ECCENTRIC I

IO5

my

walked over with a charming smile, handed over

program

booklet for autographs and casually introduced myself, pronouncing each syllable of

bombed

say, I

my name

with the greatest care. Needless to

completely. There was no sign that any one of the

crowd at the table had heard of me but as I drew back in chagrin, someone suddenly rose and dashed forward, shouting, "Gertie!"

My

wife looked startled, then cried out, "Nate!" and, behold,

they were grabbing at each other excitedly. Nate was her

whom

many

first

and he was right there at the table. She didn't need me at all. She had a great time and I stood to one side, shifting from foot to foot, and experienc-

cousin

ing,

she hadn't seen in

but not enjoying,

my

years

unaccustomed

role as husband-of-the-

celebrity.

But we should all learn from our misfortunes and humiliations and to me it was just another case of getting practice in shifting

The

viewpoints.

how many And it

universe does not revolve about me.

(I

forget

separate times I've very temporarily learned that.)

doesn't

about

revolve

though you'd never guess

it

us,

either,

collectively,

even

from a casual glance at our astronomy

texts.

For instance, any go around the little

As

under 12

No, they

long

years.

it

takes Jupiter to

And do

they say: a

don't.

happens, Jupiter goes around the Sun in one year by def-

it

inition:

very

under 12

little

Eooo mcn ^ You P^fer).

say that the

were M.oo>ooo centimeters tall (or > This means that if they were of average height to begin with, all

their

measurements have shrunk down to

they were.

To

% 7>ooo>o 00

of

what

themselves, with their shrunken atoms and their

diminished mass, they seem perfectly normal. They and their

submarine seem, to themselves, to be of normal

size

while the

THE INCREDIBLE SHRINKING PEOPLE entire universe outside the

ments by 17,000,000

submarine has increased

141

measure-

its

in every direction.

Consequently, the blood vessels are huge conduits, the white corpuscles are big enough to swallow a submarine whole without

discomfort, and so on.

The

picture

went that

anyway, but

far,

what about atoms themselves?

An atom

about M.oo>ooo700o centimeter

is

in

diameter.

In-

measurements 17,000,000 times in all directions and it becomes about % of a centimeter across. Since the important crease

its

gases in the atmosphere (oxygen

and nitrogen) are made up of

molecules which each contain two atoms, the molecules in ordinary,

unshrunken

air

would seem

ellipsoids that are

meter across at their longest diameter— at

%

of a centi-

shrunken

least to the

people.

This means that the unshrunken atoms and molecules would

be big enough to see cerned.

The

At one

as far as those

point, the submarine runs short of air

a snorkel into the patient's lungs air.

But the snorkel opening

the

air

long

it

shrunken people were con-

movie, however, does not take that into account.

is

and

not

fills

much

molecules in the patient's lungs.

would take

to

draw

air

up

its

and so

sticks

it

tanks with fresh

larger in diameter

than

Can you imagine how

through the snorkel under those

A slow leak in a tire would be speedy in comparison. What's more, once the ship is filled with unshrunken air, how do you get those huge molecules up your nostrils and into your conditions?

own shrunken

And what do you do with those your lungs? Can your own shrunken red

lungs?

once they are in

molecules corpuscles

handle them? I

had

didn't think of that

till

after I

had

finished the novel

to go back in a wild perspiration to revise several pages.

to use a device to shrink

before pulling

it

some

and I I had

of the air in the patient's lungs

through the snorkel and into the ship.

Here's another point. The men on the shrunken submarine communicated with the outside world by radio. However, the radio was shrunken and the radio waves it emitted would have

THE SOLAR SYSTEM AND BACK

142

only

% 7>ooo>o 00

shrunken

state.

might seem

the wave length they would have had in the un-

The

radio

like radio

would be emitting

They

light waves.

waves to the operator on board the sub-

men

in the

communication

radio-

marine, but they would be tiny flashes of light to the

unshrunken world and using them

for

fashion would be tricky.

And how would

our

men on

the submarine see?

By

the light

waves produced by their shrunken light sources? But these light

waves would be

gamma

rays to the outside

whose blood stream they were

in

enough

to

damage him,

I

hope, but

world— to the

cruising, I

patient

instance.

for

didn't bother to

Not

do any

calculations. I let

the radiation bit go because (once again)

I

thought of

too late and was lazy enough to feel that no one would catch

it.

it

I

underestimated my readers, of course. One sharp-minded young man picked it up and was down on me at once. I had to write back a confession of guilt.*

The movie-makers had

the heroine (Raquel

by antibodies, but hadn't the

faintest notion of

Welch) attacked what an antibody

like if it were properly enlarged. Of course, with Miss Welch on screen, who studies the antibodies, anyway? The antibodies are, of course, protein molecules and I imagined

would look

they would look like glimmering

little balls

of

wool perhaps two

inches across on the scale of the shrunken people. feel like balls of

peptide chains in place should be quite flexible and

Then,

I

had them

wool, too, for the hydrogen bonds that held the

too, the

resilient.

movie makers forgot to consider that the thin

cell membranes would not be thin at all to the shrunken people. At one point, one of the men must work his way out of the capillary and into the lung. In the movie, there's no particular problem in doing so. You just slice through the paper-thin membranes *

Since this article appeared, I received several letters pointing out additional involving electric forces, in which radical shrinking introduces

subtile ways,

insoluble dilemmas.

THE INCREDIBLE SHRINKING PEOPLE separating the two. After

membranes

all,

143

%o>ooo of an

are only

inch thick.

membrane would be scale. The plot made it

Sure, but to the shrunken people, the

something

like

40 yards thick on their

necessary for the hero to cross that thickness and

much.

yards was a bit

the book and

let it

I

go at

cheated and called

it

I

thought 40

"several yards" in

that.

What's more, there was the matter of surface tension. In the body of a quantity of liquid, each molecule is weakly attracted by all

move

cules

At the

the other molecules.

all

directions

The

attractions

come from

and cancel each other out so that individual mole-

freely as

though they are not being attracted at

surface of the liquid, a molecule

The

molecules within the liquid.

is

attracted only

all.

by other

sparse scattering of air molecules

outside the liquid has hardly any effect.

Molecules on the surface endure a net inward

and face.

it

takes an expenditure of energy for

For that reason, there

That

small as possible. freely,

is

why

What's more, far as

A

as

is

"tear-

air resistance.)

since all the surface molecules

push inward

as

closer to-

a

crowded subway car at

try to separate these

crowded-together mole-

gether, like people trying to

To

sur-

be

sphere has the smallest pos-

volume. (A falling raindrop

they can, they force themselves (so to speak)

the rush hour.

on the

small quantities of liquid, floating

assume a spherical shape.

shaped" because of

pull, therefore,

to stay

a tendency for the surface to

is

sible area of surface for its

them

push into

more energy than trying to separate ordinary molethe body of the liquid. This extra clinging-together of

cules takes

cules in

surface molecules

is

spoken of as "surface tension" and

though the liquid had a very

it

is

as

fragile skin covering its surface.

Tiny objects are not heavy enough to break that skin and small insects

can go skittering over a water surface, not because they are

floating (if they rise to

were within the body of water, they would not

the top) but because they are supported by the surface-

tension skin.

THE SOLAR SYSTEM AND BACK

144

Well, now, face tension, I

insects are light

if

what about

didn't dare calculate

would be

so great that

sur-

objects the size of our shrunken people?

surface tension of unshrunken

what the

might seem to be

liquids

enough to be supported by

shrunken people.

to the

my

I

suspect

it

heroes simply couldn't break through

the surface of the liquid blood into the air within the lung.

The albeit

necessities of the I

made him have

To

far

to let

him through,

no one has written

would be an insuperable

explain one last point,

when

So

difficulties.

say that the surface tension

tury,

me

movie plot forced

let's

in to

barrier.

go back to the nineteenth cen-

there were indeed great scientists who, like Hollywood

movie-makers, disbelieved in the existence of atoms. In the case of the scientists, ever,

it

was not a matter of

blissful ignorance,

how-

but of cogent thought.

The atomic in 1803

theory had

first

been advanced

by the English chemist John Dalton

in

its

modern form

as a convenient

way

of

explaining various chemical phenomena. Throughout the nine-

teenth century, the concept of atoms had been more and more successful in explaining

what went on

inside the test tube.

end of the century, chemists were even making use of formulas" for the more complicated molecules.

By

the

"structural

Not only

did they

count the number of atoms of the various different kinds within a particular molecule; they even placed those

arrangements in three dimensions, Naturally,

atoms

it

was almost inevitable

really existed. If

matter behave as though if it

Nevertheless,

it

much

atoms

in specific

Tinkertoy structure.

for chemists to believe that

atoms did not

tended existence explain so

thoroughly,

like a

exist

how

could their pre-

so conveniently?

How

could

were atomic in so many ways and so

were, in fact, not atomic?

some

scientists

maintained

it

was not wise to

stir

beyond the measurable phenomena. All the nineteenth-century knowledge of atoms was

indirect.

Atoms were

too small to be

seen or sensed in any direct way, and while they might be very

THE INCREDIBLE SHRINKING PEOPLE model

useful as a

lead scientists

The

to focus thought, they

who

chemist Wilhelm Ostwald. still

changed

his

Brown was

The

felt)

mis-

last to refuse

was the German physical

twentieth century opened with

vigorously maintaining the anti-atomic view. Yet he

mind, at

began

It

was

(it

literal existence.

argue in this way, the

last great scientist to

to accept the literal existence of atoms,

Ostwald

might

too easily believed in their

145

last,

and

here's

how: Robert Brown.

1827 with a Scottish botanist,

in

and

at

one time he was studying

a suspension of pollen grains in water

under a low-power micro-

He

scope.

They

found he had trouble focusing, for the grains

did not

jiggled

move

randomly

Brown and

interested in pollen

felt

all

jiggled.

purposefully in a particular direction; they over the

lot.

realized that the pollen grains

were

alive, if

dormant,

that the motion might be a kind of manifestation of

However, he watched dye similar size

particles

when suspended

ratically, too.

in water

and they

jiggled

about

Anything that was small enough would

suspension, and the smaller

it

life.

(indubitably nonliving)

was, the

of er-

jiggle in

more marked was the

jiggling-

All that could be

enon

a

by Brown, and

Why In

done

at this time

was to give the phenom-

name, since there was no explanation.

not the

it

call it

also involved the erratic

It

was discovered

motion of

particles.

"Brownian motion" then? the Scottish

1860s,

physicist

James Clerk Maxwell

produced an impressive explanation of the properties of gases terms of randomly moving particles, and for the

first

in

time the

atomic theory explained physical phenomena as well as chemical

phenomena. At once the thought arose that randomly moving particles in a liquid might be shoving the larger particles in suspension this way and that. In short, the grains of pollen or dye were being bombarded by

water molecules and

it

might be that which was producing the

Brownian motion.

Look

at

it

this

way.

We ourselves are being bombarded

from

all

THE SOLAR SYSTEM AND BACK

146 sides

by

air

molecules

or, if

we

by water molecules.

are in water,

However, at any given moment, we are being struck by enormous

numbers from itself out.

the different directions and the effect cancels

all

We are struck by no more from one direction

the opposite direction.

It

may be

more

that a few

than from

strike

from the

from the west, but the individual molecules are so tiny

east than

mere few out of the astronomical numbers immeasurably small. Of course, if a lot more strike

that the effect of a available

is

from the

east than

chance that a

lot

of the molecules

from the west, we

more is

also

will

do so

(or shrinking

their point of view the universe

molecules of

and water

air

and fewer

strike

them

bombarding mole-

will

and

larger, too.

our people reach the microscopic, they are being bom-

many

from east than from west

tiny bodies will feel

them

The

in a given small instant of time.

barded by BB-shot and not by strike

and the

Because they themselves get

as well.

individual molecules get larger

When

anything).

getting larger,

is

smaller, they present a smaller target to the

cules

random motion

immeasurably small.

But consider our shrinking people

From

but the

will feel the push,

in the sheerly

west,

and

it.

A

in the next

it

Now

a few

more

be important and

their

of them. will

if

preponderance from the east shoves

moment

a preponderance

from above

push them downward, and so on.

The random bombardment by tion in the

first

molecules would explain the mo-

place, the erratic nature of the

second, and the fact that the effect was

motion

in the

more pronounced the

smaller the floating object in the third.

Men

like

just talk.

Ostwald were not impressed by

To make

it

more than

talk

this

argument.

chances of imbalance in molecular bombardment and the the

effects.

It

was

one ought to calculate the

In short, there would have to be a

strict

size of

and rigorous

mathematical analysis of Brownian motion that would explain quantitatively in terms of the

Then

in

random bombardment

1905, such an analysis was produced,

other than Albert Einstein.

it

of molecules.

and by none

THE INCREDIBLE SHRINKING PEOPLE

147

According to his equation, particles suspended in a tainer of liquid ought to

behave

tall

in response to a balance

con-

between

the force of gravity and the effect of Brownian motion.

Gravity pulled downward and molecular motion kicked in directions,

including upward.

volved, the particles

motion were

all

would

If

gravity

all settle

were

all

all

that were in-

to the bottom. If

Brownian

that were involved they would spread out evenly.

In a combination of the two, they would spread out, but pile up

more and more densely toward the bottom. The more massive the molecules, the greater the Brownian motion particular size at a particular temperature

for

objects of

a

and the smaller the

extent to which they would crowd toward the bottom. Einstein was merely a theoretician, however.

He

was

satisfied

and he left it to others to check it against observable phenomena. The one who followed it up was a French physicist, Jean Baptiste Perrin. In 1908, he suspended small particles of gum resin in water and counted the number of particles at different levels. He found that the numbers increased to produce the equation

as

he worked downward exactly

in

accordance with Einstein's

equation, provided the molecules of water were given a certain

mass.

Not only had he

verified Einstein's explanation of

motion, but he was the

first

to

Brownian

work out a reasonably accurate

measure of the actual weight of individual molecules.

Ostwald was now faced with an observable individual molecules.

By

effect

produced by

looking at suspended objects in water

effect, see them being struck by inThat supplied his rigid requirement for direct observable evidence and he could no longer deny the existence of

jiggling around,

he could, in

dividual molecules.

atoms. Perrin received the 1926

Nobel Prize

in Physics for his work.

(Einstein had gotten his, for other work, in 1921.)

This brings

me

back to Fantastic Voyage. In the movie, the

shrunken submarine moves through the blood stream precisely as

THE SOLAR SYSTEM AND BACK

148 it

would

if it

were of normal

That would be

rent.

so

moving through an ocean

size

no atoms

there were

if

or

if

cur-

atoms were

infinitesimally small.

But there

The

are

atoms of

size

comparable to the shrunken

ship.

ship ought therefore to be jiggling from side to side, back

and

up and down, and every direction in between, through the effect of Brownian motion. This would happen in even more pronounced fashion to the individual people on those occasions when they left the ship to swim around in the blood stream. I couldn't actually allow much Brownian motion in the novel. forth,

would have introduced too many complications (bad seasickness for one thing). I did mention it, though, and allowed some It

show

jiggling at the start, just to

then

I

ignored

All this

of

my

fiction

to

do

may

I

and who now think Don't think that

not necessarily require Despite

there;

and

it

felt

the impulse to write science

advanced degrees in science

requires

for a

moment. Good

science fiction does

the errors, inconsistencies, and oversights in the

all

penseful, fast-moving, I

ought to be

all this folderol.

movie Fantastic Voyage, a bit while

it

cause alarm and despondency in the hearts of some

Gentle Readers who have

so.

knew

it.

thought

I

and

it

delightful.

was a

The

lot of fun, very sus-

errors didn't

bother

me

was watching.

What's more,

if

someone

else

had written a novel based on the errors, it would

movie and had not bothered to correct any of the still

easily

have made an exciting

It's just that,

were there and

I

in

had

ing science fiction to say that

only way.

I

my own

story.

case, I

to correct them.

and

consider

it's

know the errors my personal way of writ-

happened It's

to

not the only way. Candor compels

my way

the best way, but

it's still

me

not the

B

— CHEMISTRY

THE FIRST METAL

11

I

am

sometimes asked how

essay.

The answer

is

Sometimes, though,

I

I

decide on the subject for a science

and straightforward:

clear

do happen

I

don't know.

to catch a fugitive glimpse of

the mental processes involved before they whiff away and depart forever.

Thus, several weeks ago,

I

came

across

some comments

chemistry journal concerning the metal, gallium. This interesting metal

on two counts.

It

is

in a

a very

played a melodramatic role in

the working out of the periodic table, and

it

has a very interesting

melting point.

That gave

rise to

the possibility of an essay on the periodic

ble or, alternatively, to

few moments,

I

ta-

one on melting points of metals. For a

speculated idly on what could be done with melt-

ing points. It seemed to

me

melting point of gallium,

I

that

would

I

if

first

were going to discuss the

have to discuss the melting

point of mercury.

And to

if I

discussed the melting point of mercury,

mention a few other things about

it,

I

would have

notably the fact that

it

was one of the seven metals known to the ancients. In that case,

how about an

essay,

first,

on the ancient metals?

THE SOLAR SYSTEM AND BACK

152

That

what

is

my way And

up

am now

I

to mercury,

that

is

how

I

sitting

down

and then

to write, intending to

work

to gallium.

decide on subjects to write

about— at

least,

in this case.

The order)

seven metals

known

to the ancients were (in alphabetical

copper, gold, iron, lead, mercury,

:

covery of each of these strongly suspect

that was the

Why

it

first

is

lost

silver,

and

tin.

The

in the mists of the past,

was gold that was discovered

first.

It

dis-

but

I

was gold

metal.

Gold can occasionally be found as a glittering little nugget. Its bright and beautiful yellow color would easily attract the eye and it would become an ornament at once. Once handled, gold would almost at once show itself to be a remarkable substance, much different from the rock, wood, and bone that mankind had been working with for hundreds of thousands of years. Not only would it have a shiny color, but it would be considerably heavier than an ordinary pebble of the same size. Then, too, suppose the finder wished to work the nugget into a more symmetrical shape. To shape a stone, he would make use of not?

careful strokes with a stone chisel. Flakes of thin stone split off

The merely

would

the object being shaped.

gold would not behave in this manner.

make

The

chisel

would

a dent in the gold. If the gold were beaten with a

mallet, the metal

would not powder

as a

pebble would;

flatten into a very thin sheet. It could also

it

would

be drawn out into a

very fine wire, which stone certainly could not do.

Other metals were eventually discovered— other objects which had luster and unusual weight and which were malleable and ductile. None was as good as gold, though. None was as beautiful,

or as heavy.

shine

more

What's more, other metals tended

or less quickly

if

exposed to

air

to lose their

over periods of time;

gold never did.

And rare.

gold had another property which added to

This was

true, to a

somewhat

lesser extent,

its

value;

it

was

however, of the

THE FIRST METAL other metals, too.

The

Earth's crust

153

primarily rock, and the oc-

is

The

metal nugget was occasional indeed.

casional

"metal" seems to

come from

very

word

the Greek word metallan, meaning

"to search for/' a tribute both to

and

its rarity

desirability.

Modern chemists have worked out the composition

the

of

Earth's crust in terms of each of the various elements, including

the seven ancient metals. Here in Table 32 are the figures for the

grams of metal per tons of Earth's

seven, given in

crust,

and

in

order of decreasing concentration.

Table Metal

32

Concentration (g/ton)

Iron

50,000

Copper Lead Tin Mercury

As you

see,

centration

80 15 3

0.5

Silver

0.1

Gold

0.005

gold

is

by

far the rarest of the seven metals.

g ram P^r ton

of 0.005

is

equivalent to

1

A

con-

part

in

200,000,000. Still,

the total quantity of gold

entire crust.

At

is

sizable

this percentage, the total

if

one considers the

mass of gold there

is

about 155,000,000,000 tons.

There

is

gold in the ocean, too, in the form of submicroscopic

metallic fragments,

gram per

ton,

which comes to a concentration of 0.000005

making a

mass in the oceans of nearly

total gold

9,000,000 tons.

The

gold in the ocean

is

so

dilute

that

it

extracted at anything but a large loss. Therefore

been extracted from the ocean. of gold, but the soil

is

The

soil

cannot yet be

no gold has ever

has a larger concentration

harder to work with.

If

gold were evenly

THE SOLAR SYSTEM AND BACK

154

spread throughout the crust, that gold, too, would be unavailable to us.

But the gold profitably,

is

not evenly spread. There are occasional acces-

where the gold content

sible regions

high enough to be mined

is

even with primitive equipment, and where reasonably

pure metallic gold can sometimes be found in sizable nuggets.

But only

a tiny fraction of

the gold

all

is

thus

made

available.

Nothing has been

so avidly searched for as gold through all six

thousand years of

civilized history; yet

estimated that the total

amount

with

of gold

ground by mankind amounts to only 50,000

all

that search

extracted tons.

it

is

from the

What/ s more,

the world's mines are producing gold at the rate of only about a

thousand tons a year (half of

in

it

South Africa). Even

so,

the end

of Earth's reserves of minable gold seems to be in sight. It

would be

interesting to see

served to affect

human

how

small a quantity of gold has

history in so

enormous

a way. If all the

gold so far extracted from the Earth were packed into a cube, that

cube would be 290 feet on each plate an area the size of

only be about

1

side. If all that

Manhattan

It

would

millimeter thick. (That puts another view on the

old immigrant notion that the streets of

with gold.

gold were used to

Island, the layer of gold

would have

to be, at best,

New

York

are paved

an awfully thin pave-

ment.)

The first

question then arises as to

metal to be discovered

The answer

lies in

if it

why

gold should have been the

was the

rarest of the seven.

the comparative activity of the metals, their

comparative tendency to combine with other elements to form nonmetallic compounds.

The

activity of metals

can be measured as "oxidation potential"

in volts (because electric currents can

make

metallic atoms plate

out as free metals or go into solution as ions).

drogen

The element

hy-

(which has some metallic properties from a chemical

standpoint)

is

arbitrarily given

an oxidation potential of 0.0

volts.

THE FIRST METAL

155

Elements which are more active than hydrogren have a positive oxidation potential; those

less active, a

negative one.

Here, then, in Table 33, are the oxidation potentials for the seven ancient metals:

Table Metal

Oxidation Potential (volts)

Iron

Silver

+0.44 +0.14 +0.13 -0.34 -0.79 -0.80

Gold

-1.50

Tin Lead Copper Mercury

As you and

is

see,

gold

is

by

therefore

form. Thus, gold

is

by

So

likely to it

all.

most

likely to exist in

free metallic

common than iron, atom by atom, but more common than iron nuggets. Indeed,

far less

but for one factor which not be found at

far the least active of the seven metals,

far the

gold nuggets are far

more

33

I will

come

be noticed than the

happens that while

silver

would

to soon, iron nuggets

Furthermore, the yellow gleam of gold

is

much

dirty gray of iron.

and copper objects

(also

among

more inactive metals) can be found in predynastic Egyptian tombs dating as far back as 4000 B.C., gold objects, it is thought,

the

antedate that mark by several centuries. In early Egyptian history, silver was more expensive than gold,

simply because

it

was

rarer in

nugget form.

we might generalize that the ancient metals are the metals. Yet we are bound to ask, then, if there were any metals not known to the ancients. The answer is: Yes.

Indeed, inert inert

There are

six

metals of the "platinum group"—platinum

itself,

then palladium, rhodium, ruthenium, osmium, and iridium— that should qualify. Platinum, osmium, and iridium are somewhat more

THE SOLAR SYSTEM AND BACK

156

inert than gold, even,

Why,

silver.

and the others are

known

then, were they not

tempting to blame

It is

them— ruthenium,

it

on the

at least as inactive as

to the ancients?

Four of

rarity of the metals.

rhodium, osmium, and iridium— are consider-

ably rarer even than gold, with concentrations in the crust of only 0.001

gram per

ton. They, along with rhenium, have the distinc-

tion of being the least

discovered— but that

Yet platinum

mon.

common

metals on Earth.

unique distinction of being the

also the

as

is

last stable

element to be

another story.)

is

common

as gold,

and palladium twice

gold nuggets can be found, then,

If

(Rhenium has

why not

as

com-

nuggets of

platinum? Or palladium?

For one thing, yellow gold

far

is

more noticeable than white

platinum. For another, the best platinum ores are located no-

where near the ancient sites of civilization in the Middle East. Then, too, I rather suspect that platinum nuggets were indeed found now and then— and mistaken for silver. Platinum is far less malleable than tive

silver

and

is

not easily worked.

can see the primi-

metalworker looking at such nuggets in disgust and mutter-

ing "Spoiled silver" as he tosses

The apparent resemblance It

I

was

first

them away.

to silver

marks platinum to

clearly recognized as a distinct

a Spanish chemist,

Don Antonio

this day.

metal in 1748, when

de Ulloa, described samples of

the metal which he had located in the course of his travels

through South America. Spanish word for

name)

Nor

silver.

He named

it

"platina" from plata, the

So platinum remains forever

is it

common

surprising, in

view of

all this,

that iron, by far the most

of the seven metals— five hundred times as

the remaining six put together— lagged in

all

the

(at least in

a kind of silver.

rest.

After

all,

it

common

as

some ways behind

was the most active of the ancient metals,

the most apt to be in combination, the most difficult to loose from that combination.

That

it

was known at

all

may have been

catastrophe millions of miles from Earth.

the result of a cosmic

THE FIRST METAL After

all,

as

as

far

157

chemical principles are concerned, iron

should occur on Earth only in the form of nonmetallic com-

pounds, never as the free metal. Yet that's not the way

There

is

ward the

much

so

iron

itself, this

it is

and

seems that one of them

it

may have exploded

(the one, presumably, between

Jupiter, the orbit of

which

plosion

a

must be other

doesn't affect Earth's crust, but there

planets with such a nickel-iron core

fragments of that explosion).

is

metal, nickel, in a 10-to-i ratio.

its sister

is

it is.

so concentrated to-

mass of the planet

center, that one-third of the

liquid core of iron plus

In

on Earth, and

Mars and

now marked by the asteroids, The smaller fragments of that

bombard the Earth, and some

the ex-

of

them

are the fragments

is

large

enough

of the nickel-iron core. If the fragment

it

survives

the friction of the atmosphere and strikes the crust, where

it

lodges as heaven-born "nuggets" of iron.

Small pieces of nickel-iron (undoubtedly meteoric in origin) are

found

in

Egyptian tombs dating back to 3500

b.c.

They

are there

in the guise of jewelry.

As long they were

be used when found as nuggets,

as metals could only

bound

to be excessively rare, but

some time before 3500

the true discovery of metals was made.

b.c.

could stumble across a nugget. nize

The

fool, after all,

took a man, however, to recog-

It

what had happened when copper nuggets were found

ashes of a It

Any

fire

that

had been

built

in the

on a blue stone.

was a daring thought that from rock one might gain metal. science of metallurgy began

and men began to look not

for

metal only, but for metal ores— for rocks that, on heating in a

wood It

fire,

would

yield metal.

was copper that was

chiefly

became the wonder metal of the

mon it

as

as gold,

produced age. It

in this

manner, and

was 16,000 times

once the ores were taken into account.

as

it

com-

And though

compounds in the ore, it was not so active bound in those compounds. A gentle nudge,

did occur as rocklike to

be

tightly

chemically speaking, would suffice to pry the copper loose.

Copper alone was

ornaments and for some But then another accidental

suitable merely for

utensils— too soft for anything

else.

THE SOLAR SYSTEM AND BACK

158 discovery

must have been made. Tin and

as copper ores were,

some

if

ores could be handled

ores contained both copper

the mixed metal ("alloy") that resulted was

tin,

tougher than copper alone. cients learned to

mix

We

and

ores of copper

tin

the Bronze Age. In the Middle East, the

for

the Bronze

Tin was the bottleneck here. and the still

tin reserves of

navigators, the best

way out

their

The

an-

Thus was

site of

b.c.

initiated

man's oldest

and endured

It is

% 5 as common as copper,

only

the Middle East ran out while copper was

As

had

to

be scoured

a result, the far-distant

The

for tin.

Phoenician

and most daring of the ancient world, made

to the

"Tin

Isles" for

the purpose.

Phoenicians kept the secret of the location of the Tin

throughout their history, but sailing

The

years.

available in comfortable amounts.

corners of the world

and

harder and

on purpose and to

Age began about 3500

something over two thousand

much

the alloy "bronze."

call

use the bronze they obtained for war weapons.

civilizations,

much

it

Isles

seems quite certain that they were

out into the Atlantic Ocean and northward to Cornwall,

on the southwestern extremity of the Cornwall

is

island of Great Britain.

one of the few regions of the Earth which

is

rich in

mining, some 3,000,000

tin ore. In twenty-five centuries of steady

tons of tin have been removed from the Cornish mines and the area

is

not yet exhausted. Nevertheless,

minute compared to those of the

its

output these days

relatively

is

untapped mines of

Malaysia, Indonesia, and Bolivia.

Yet even while bronze was carrying

knew

tools. It

now and

it,

the ancients

much

better for

war weapons

was iron— those metallic lumps that were picked up

then, a very rare

now and

There were, of course, iron

and

before

very well that there was a metal that was harder and

tougher than bronze and potentially

and

all

tin ores. Indeed,

common. The

it

then.

ores, just as there

were copper ores

was obvious that iron ores were extremely

trouble was that iron

(much more

active than cop-

THE FIRST METAL per) held on to

its

compound

place in the

The

techniques for iron.

as was coaxed out of the ore was riddled with gas bub-

was

bles. It

firmly.

would not do

that sufficed to extract metallic copper

Such iron

159

Special

and good

brittle

techniques

for nothing.

involving

hot

particularly

needed, along with high-quality charcoal. Even

were

flames

when temperatures

were reached that sufficed to melt the iron and drive out the bubbles and, indeed, prepare

it

in pure form, the end-product

was

disappointing. Iron obtained from ore was not nearly as hard as

the meteoric nuggets, and

it

did not hold nearly as fine an edge.

The difference was that meteoric unknown to the ancients).

iron contained nickel (a metal

But then processes were developed that produced iron into which some carbon from the charcoal was introduced. In kind of

steel

was produced and

that, at last,

effect, a

was the metal that

was needed. It

was sometime about 1500

good iron

in useful quantities

when

b.c.

the secret of producing

was developed somewhere

in the

southern foothills of the Caucasian mountains. This was in what

was known

as the

kingdom

Ark landed). The area was, Hittites, tite

of Urartu (the "Ararat" at the time,

whose power center was

kingdom

where Noah's

under the control of the

in eastern Asia

Minor. The Hit-

keep knowledge of the new technique a

tried to

monopoly, but the exploitation of

this

new weapon was

slow. Be-

fore the Hittites could really turn the metal into a world-beating

military resource, they

of civil

The

were themselves beaten by a combination

war and invasion from without. fall

of the Hittites

of iron technology

fell

came soon

after 1200 b.c.

and the

secret

to Assyria, the land just south of Urartu.

Gradually, the Assyrians developed iron to an unprecedented extent

and by 800

into the field.

nium and syrians

b.c.

they were putting a completely iron-ized army

They

for a similar purpose.

swept

all

we

stockpile ura-

For two hundred

years, the As-

stockpiled iron ingots as

before

them and

built the greatest empire the

:

THE SOLAR SYSTEM AND BACK

l6o

Middle East had yet seen— until

their victims learned iron tech-

nology for themselves. It is interesting to note,

monness,

is

not the most

by the way, that

common

iron, despite its

metal on Earth. There

com-

is

one

metal more common, but also more active. In consequence,

it

lagged even farther behind in development.

The most common metal centration of which

mon

as

iron,

but

is

in Earth's crust

is

81,300 grams per ton.

its

oxidation

aluminum, the con-

It is 1.6

potential

is

times as com-

+1.66,

which

is

considerably higher than even that of iron.

This means that the tendency of aluminum to form compounds

and that it is much more difficult compounds than it is to force iron of those out of its compounds. Moreover, no aluminum nuggets fell from the sky to hint to mankind that such an element exists. As a result, aluminum remained completely unknown (as a is still

greater than that of iron,

to force

aluminum out

free metal) to the ancients. It wasn't until 1825 that the first piece

of

aluminum metal

(quite impure) was forced out of a

by the Danish chemist Hans Christian Oersted.

And

it

compound wasn't

till

1886 that a good method was discovered for producing the pure metal cheaply and in quantity.

Metals, generally, are denser than stone. in ounces per cubic inch,

we

find (see

Table

If

we measure

Table 34)

34

Density

Metal

(ounces/ cubic inch)

Tin

4.2

Iron

4.6

Copper

5-2

Silver

6.1

Lead Mercury Gold

6.6 7-9 11.3

density

THE FIRST METAL

l6l

Since the typical rock has a density of about 1.6 ounces per cubic inch, even the least dense of the seven metals

dense as rock, while gold

High density has

is

its uses. If

you wish to pack a

denser the metal the better. Gold

is

cury, being liquid,

That

would be too hard

came the

it is

it is

too valuable. Mer-

to handle.

leaves lead as a third choice. It

and

metal,

weight into

the best in this respect but no

going to use gold as routine ballast;

is

lot of

you would use metal rather than stone; the

a small volume,

one

2.5 times as

is

about seven times as dense.

is

relatively cheap, for a

four times as dense as rock. Lead, therefore, be-

The

representative of heaviness.

phrase "heavy as lead"

has entered the language as a cliche, which has

much more

force,

through sheer repetition, than the phrases "heavy as gold" or

(We mean

"heavy as platinum."

"dense" rather than "heavy," but

never mind.)

we

Again, can't

and

speak of "leaden eyelids" to imply sleepiness that

be fought

difficult

To

off;

"leaden steps" to indicate a walk

made

slow

by the weight of weariness or sorrow.

hang

force a line to

vertically,

one would want to put a

weight at one end, so that the force of gravity would stretch the line straight

up and down.

A lump of lead would be a

compact way

of supplying the weight.

The what

Latin word for "lead"

a

"plumb

line"

lead to a line you as far as possible,

must

wanted

is

plumbum and now you

be. Since to

can see

you would attach a piece of

throw into the ocean and have sink

you see what "to plumb the depths" means.

Again, since the ancients believed that the heavier an object the faster faster terials.

it fell, it

seemed

to

them

that a lead weight

than the same-sized weight made of other

less

would

fall

dense ma-

So you see what "to plummet downward" means.

Finally, since a lead

weight makes a line completely

there grew to be a tie-in between lead

now you

see why, in a

and completeness,

Western movie, the old rancher

vertical,

so that

says to the

young schoolmarm, "By dogies, Ah'm shore plumb tuckered out,

THE SOLAR SYSTEM AND BACK

l6l

missie." (At least

you know why he says

it if

you know what the

other words mean.) All this remains, even though, in addition to gold six

now known,

other metals,

newcomers

—platinum,

than gold.

Osmium

rocks.

has a density of 13.1 ounces per cubic inch

is

far

behind.

point. Metals, generally, are lower-melting than

Rocks melt,

C. This

and mercury,

Three of these

osmium, and iridium— are denser, even,

and the other two are not

One more

are denser than lead.

in general, at temperatures of 1800

most

to 2000

high enough to allow rocky materials to be used to con-

struct furnaces

and chimneys. Here

in

Table 35 are the melting

points of the seven ancient metals:

Table 35 Metal

Melting Point (° C.)

Iron

1535 1083

Copper Gold

1063

Silver

961

Lead Tin Mercury

327 232

-39

Iron has quite a high melting point for a metal, which

the reasons crack.

it

was a hard nut, metallurgically,

Copper,

silver,

look at lead and

Lead and ture of the

and gold are

is

will

but

melt in any ordinary flame, and a mix-

melt at lower temperatures than either

"solder." It can

be

C. Such an alloy of

easily melted,

poured onto the

between two pieces of metal, and allowed to

Tin containing

for the ancients to

in the intermediate range,

separately— temperatures as low as 183

and lead

one of

tin.

tin are easy to

two

is

a little lead

is

tin

joint

freeze.

"pewter." Kings and nabobs used

gold and silver plates to eat from, despite their expense and

diffi-

THE FIRST METAL

163

culty of working, out of a sense of conspicuous consumption.

Poor people used clay and wood, which were

ugly. In

between,

there were pewter dishes. It

was particularly easy to work either

there is

is

a tale to

tell

tin or lead into tubes,

and

about each. Ordinary metallic "white tin"

stable only at relatively

warm

begins to be a tendency for

it

temperatures. In winter cold there

crumbly nonmetallic

to turn into a

"gray tin." This takes place slowly unless temperatures consider-

ably below zero are reached.

A

cathedral at St. Petersburg, Russia, installed a magnificent

organ with beautiful tin pipes. pipes disintegrated. That's

and gray

tin

tin,

but

I

Came

how

a cold, cold winter

and the

chemists discovered about white

doubt that the cathedral personnel were

particularly overjoyed at their contribution to scientific knowledge. It is all

very well to build organ pipes out of tin, but for ordinary

plebeian water pipes, tin was too expensive.

The

other low-melting

Roman Empire where city of Rome itself, for

metal, lead, was used. In those parts of the a central water supply was set

up

instance), lead pipes were used.

the fellow

who

it

And now you know why we

call

deals with water pipes a "plumber," even though

the pipes are no longer

As

(in the

made

happens, and as the

of lead.

Romans

did not know, lead com-

pounds are strongly and cumulatively poisonous. Under conditions, small quantities of the lead pipe

the water supply would

would

become dangerous over

certain

dissolve

and

longish periods.

There are even some who have recently suggested that the

Roman Empire ernment and

fell,

in part at least, because

social leadership in the city of

from "plumbism," that

But neither

silver

is,

tion

I

men

nor lead

is

the lowest-melting of the seven is still

held today) by

that brings us back one step in the chain of rumina-

described at the start of this chapter.

Mercury

of the gov-

were suffering

from chronic lead poisoning.

ancient metals. That record was held (and

mercury— and

key

Rome

will

be the subject of the next chapter.

THE SEVENTH METAL

12

It is

very difficult for an ivory-tower chemist such as myself to dem-

onstrate competence in the practical aspects of the science. Consequently,

always with a sinking heart that

it is

me

approaching

I

watch anyone

with a down-to-earth problem in chemistry.

It

always ends in a personal humiliation.

Well, not always.

Once, wife to

my I

in the days

came

to

me

wedding

I

was working toward

"Something," she

I was had time

still

in

my

my

me

She handed yet

it

waited and

me

but

I

had

incompetence many times

was her gold wedding

I felt,

said, "I

"But

the ring and, indeed,

it

do

so again.

that's impossible!"

had the appearance of

ring, inscription

uneasily, that she suspected

ring of low-grade gold. I

my

censoriously, "It's turned into silver."

stared at her with astonishment.

silver,

Ph.D.,

"What happened?"

She eyed I

my

"has happened

early stages as a chemist,

to demonstrate

over. I didn't enjoy the prospect of having to I said,

said,

ring."

winced.

already

when

in alarm.

Yet

I

and

all.

She

had bought her a

could think of nothing!

just can't explain this.

nothing in the world—"

I

Except for mercury,

there's

THE SEVENTH METAL "Mercury?" she

"How

with rising inflection.

said,

l6$

know

did you

about the mercury?" I

had apparently

magic word.

said the

happened. Inflating

my

I

saw instantly what had

chest and putting on an air of lofty con-

"To the

chemist's eye,

sideration,

I said,

vious that

what one has here

dear,

it is

amalgam and

gold

is

my

at once ob-

that you've

been handling mercury without removing your wedding ring first."

That was

of course.

it,

At the laboratory

mercury and was fascinated by it

so

it

I

brought

amuse myself with now and then.

to

fashion

couldn't resist pouring a drop into the

could play with

rapidly mixes with gold to

Yet despite

this sadly

mercury's fascination, cient

man

palm of her hand ring

silvery gold

so she

on and mercury

amalgam.

dramatic and highly personal instance of discussed the seven metals

known

to an-

in the preceding chapter with hardly a word for the

them— mercury. But

most unusual of merely saving

Mercury

I

form a

a small vial of

around in enticing

wife found the vial and

But she kept her wedding

it.

had had access to

home

(It rolls

My

and doesn't wet anything.)

I

is

it

for a chapter of

its

that wasn't neglect;

riddled with exceptional characteristics.

for instance, that

it

was the

strongly suspect that

it

was

I

own. I

am

sure,

least familiar of the seven metals

was the seventh metal (and the

and

last)

to

be discovered by the ancients.

As

for its

being the least familiar,

has to say about

it, if

written by people

only because

who had

little

or

we might

it is

no

a long

see

what the Bible

and

intricate

interest in science. It

book might

therefore be considered the authentic voice of the ancient nonscientist.

Gold, of course, all,

is

the standard of excellence and perfection to

even to the Biblical writers.

gold

is

to give

it

To

say something

is

more than

the highest possible worldly praise. Thus:

THE SOLAR SYSTEM AND BACK

l66

Psalms 119:127. Therefore I love thy commandments above gold; yea, above fine gold.

And

what do the

as nonscientists,

Biblical writers say

about

the other metals? For economy's sake, I've searched for a verse

many

that mentions as

Ezekiel

quoting

is

metals as possible, and here's one where

God

among

threatening the sinners

as

the

Jews:

Ezekiel 22:20. lead,

to

it,

and

The

and

As they gather

and

silver,

brass,

and

iron,

and

the midst of the furnace to blow the fire upon so will I gather you in mine anger and in my fury,

tin, into

melt

it;

you

I will leave

there,

and melt you.

compared to the various metals, notably

sinners are

ex-

cluding gold, to show that they are imperfect.

Here, by the way, of the

and

we must remember

that the English words

King James version are translations of the

may be

mistranslations.

was used indiscriminately

and

loy of copper

tin.

all

al-

version invariably trans-

an alloy of copper and zinc and

is

The

not what the Biblical writers meant. sion replaces

Hebrew

pure copper and for bronze, an

The King James

which

lates it as "brass,"

for

original

The Hebrew word nehosheth

is

Revised Standard Ver-

the "brass" in the King James with "bronze" or

"copper." If

we

substitute copper for brass in the verse

will see that I

to

mention

tin,

and

have managed, by using merely two Biblical of the ancient metals: gold,

six

lead.

from Ezekiel, you

That

leaves only mercury.

silver,

What

verses,

copper, iron,

does the Bible say

about mercury?

The answer is: Nothing! Not a word! Not in the Old Testament, Apocrypha.

It

was the most

seems clear that of

or the

New,

or the

the seven metals, mercury

exotic, the least used for everyday purposes,

most nearly what we would today

The

all

nonscientists

who wrote

call

the

a "laboratory curiosity."

the Bible were so

little

acquainted

THE SEVENTH METAL with

it,

they never had reason to mention

167

even in figures of

it,

speech.

As to

to

me

why

to

should be the

it

be no mystery.

across

comparatively

It is

and gold are

metals, only silver

be discovered; that seems

last to

less

rare, for of

the seven

common. Nor does one come

mercury ingots, naturally, since

it

liquid at ordinary

is

temperatures.

What

led to

its

discovery was the accident that

tant ore was brightly colored. This ore ically speaking, is

sulfur. It

When

mercuric

sulfide, a

is

its

one impor-

"cinnabar," which, chem-

compound

of mercury

and

has a bright red color and can be used as a pigment.

so used,

it is

word

also applied to its

in considerable

demand and, unwhen it was acci-

called vermilion, a

color.

Cinnabar must have been

doubtedly, there must have been occasions dentally heated to the point where

of metallic mercury. There that mercury was b.c.

known

is

it

broke up and liberated drops

evidence in the Egyptian tombs

in that land at least as far

This sounds ancient enough but compare

back as 1500 with copper,

it

and gold, which date back to 4000 b.c. Even after mercury had been isolated, there seems

silver,

new and may have made it too

difficulty in recognizing it as a

that

it

was liquid

to have

separate metal. different

metals to put on a par with them. Perhaps

it

been

The

fact

from the other

was only one of

the other metals in molten form. It

had the look of

ver? Silver to a

itself,

silver

about

ordinary solid

it.

Could

silver,

it

be, then, liquid

could be melted

good red heat, but mercury was a liquid

temperatures.

To

silver,

sil-

raised

ordinary

the ancient workers, such a difference was per-

haps not as significant as hot liquid

silver at

if

why not

it

would be

to us. If there could

be a

a cold one?

In any case, whatever the thought processes of the early discoverers of mercury,

it

remains true that mercury was the only

one of the seven metals not given a name of

its

own. Aristotle

THE SOLAR SYSTEM AND BACK

l68 called

it

and

"liquid silver" (in Greek),

physician Dioscorides called

The

the same thing.

came hydrargyrum

it

in

Roman

"water-silver,"

times the Greek

which

essentially

is

name is hydrargyros in Greek and beLatin. And in fact, the chemical symbol

latter

in

for mercury remains

Hg,

honor of that Latin name,

in

to this

day.

The Roman

writer Pliny called

The

"living silver."

reason for this

and motionless (that

moved under

is,

it

is

argentum vivum, meaning

that ordinary silver was solid

"dead") whereas mercury quivered and

slight impulse. If a

drop

fell,

it

shivered,

and the

away in all directions. It was "alive." An old English word for alive was "quick." We still use it with that meaning in the old phrase "the quick and the dead." We still droplets darted

say that vegetation "quickens" in the spring. If

outermost dead callus of the neath,

we

we

cut past the

skin, to the soft, sensitive tissue be-

"cut to the quick."

Naturally, "quick" characteristics of

comes

there are forms of

to

be applied to the more notable

one of which

life,

is

rapid motion.

To be

sure,

such as oysters, sponges, and mosses, which

life,

commonThey knew the dis-

don't show notable motions, but the language-making

no such

alty indulged in

tinction

"quick"

side-issues.

between a race horse and a hobbyhorse. Consequently,

came

to

mean

Nowadays, that thing

fine

else,

and

last

"rapid."

meaning of "quick" has drowned out

the older

meaning

every-

remains only in the old cliches

that never die and that remain to puzzle innocents.

would imagine that "the quick and the dead"

(Moderns

refers to

Los An-

geles pedestrians.)

Keeping can be

all this

in

mind, we see why Pliny's argentum vivum

literally translated as "quicksilver,"

old English

Where,

name

for

then, did the

The medieval

and that

is,

indeed, the

it.

name "mercury" come from?

alchemists approached

their

oughly mystical manner. Since most of them

work (not

a

thor-

all!)

were

in

THE SEVENTH METAL

169

incompetent, they could best mask their shortcomings by indulg-

What

ing in windy mysteries.

the public could not understand,

they could not see through. Naturally, then, alchemists favored metaphorical speech. There

were seven different metals and there were also seven different planets,

and

surely this could not

be coincidence, could

not, then, impressively speak of the planets

it?

Why

when you meant

the

metals?

Thus, the four brightest of the planets, in order of decreasing brightness, were the Sun, the

match these with

Moon, Venus, and and

gold, silver, copper,

Jupiter.

Why not

tin respectively, since

these were the four most valuable metals in order of decreasing value?

As

for the

others— Mars, the ruddy planet of the war god,

naturally iron, the metal out of

(As a matter of iron rust in

To

wonder

you carefully

else,

you can

select

matched

to the

sort of coincidence that causes

mod-

"there might not be something in

is

bound

to

al-

make words now and then and

out the words and don't touch anything

convince yourself that nonsense

easily

The slow-moving ness.

if

Mars may be due

counter that, one need only say that any random

succession of syllables if

which war weapons are made.

the ruddiness of

its soil. It's this

ern mystics to

chemy."

fact,

is

Saturn, slowest of

all

is

the planets,

to lead, the proverbial standard for dullness

sense.) is

naturally

and

heavi-

Mercury, on the other hand, which swings rapidly from one

side of the

Sun

to the other,

is

equated with the darting droplets

of quicksilver. (Thus, the seventh metal

enth planet. See Chapter

Some

of these

old-fashioned

i.

comparisons

names

is

matched with the

sev-

Pure coincidence!)

for certain

still

hang on

compounds.

in

the

form of

Silver nitrate, for in-

stance, appears in old books as "lunar caustic" because of the sup-

posed relationship of

compounds used

as

silver

and the Moon. Again, colored iron

pigments are sometimes called by such names

THE SOLAR SYSTEM AND BACK

17O

"Mars yellow" or "Mars

as

red."

Lead poisoning was once

referred

to as "saturnine poisoning."

The

only planet to enter the realm of modern chemistry in a

way was Mercury.

respectable

It

became the name of the metal, came about because

ousting the older quicksilver. Perhaps this

chemists recognized

name and

that

quicksilver

was not an independent

that mercury was not merely silver that was liquid or

quick.

Oddly enough, metals were named for planets in modern times, too, and the modern names stuck, of course. In 1781, the planet Uranus was discovered, and in 1789, when the German chemist Martin Heinrich Klaproth discovered a new metal, he named for the

new

planet and

it

became "uranium." Then,

when two metals were found beyond uranium,

it

in the 1940s,

they were

named

two planets, Neptune and Pluto, that had been found beyond

for

Uranus.

The new

Even the two

metals became "neptunium" and "plutonium."

asteroids got their chance. In 1801

and

and 1802, the

first

were discovered (see Chapter 4). Klaproth discovered another new metal in 1803 and promptly asteroids, Ceres

Pallas,

named it "cerium." The same year, an English chemist, William Hyde Wollaston, discovered a new metal and named it "palladium."

Mercury gained unusual

distinctions during the

Middle Ages.

Throughout ancient and medieval times, the chief source of mercury was Spain, and the Moorish kings of the land made spectacular

use of

it.

Abd ar-Rahman

III,

the greatest of them, built a

palace near Cordova about 950, in the courtyard of which a

fountain of mercury played continuously. Another king was sup-

posed to have slept on a mattress that floated in a pool of mercury.

Mercury gained another medieval stract nature. It

val alchemists

distinction

of a

more

ab-

seems that one of the chief aims of most medie-

was the conversion of an inexpensive metal

like

lead to an expensive one like gold.

That

this

could be done seemed likely from the old Greek no-

THE SEVENTH METAL tion that all matter

was made up of combinations of four basic

substances, or "elements/' which were called "air,"

and

we

stances

"fire,"

These were not

bad guess

The medieval ever. It

"water,"

common

sub-

by those names, but were abstractions which might

call

really a

"earth,"

identical with the

better be translated as "solid," "liquid," "gas,"

not

171

and "energy."

It

was

for the times.

alchemists went beyond the Greek notions, how-

seemed to them that metals were so

different

from the

ordinary "earthy" substances, like rocks, that there must be a particular metallic principle involved.

"earth," ciple,

made

This metallic principle, plus

a metal. If one could but locate the metallic prin-

one could add "earth"

in different

ways to form any metal,

including gold. Naturally, solidity to it

then?

It

and produced a

principle,

What

solid metal.

was a liquid and that must be because

"earth" in

some

by adding "earth" to the metallic

it.

Perhaps what

little it

about mercury, so little

itself.

began to work with mercury indefatigably, and

since mercury vapors are cumulatively poisonous,

many

had

it

did have could be removed in

fashion, leaving the metallic principle

Many alchemists

one added

wonder how

I

them died prematurely. The vapors affect the mind, too, but I suppose it's hard to tell when an alchemist is speaking real gibberish. For that matter, I wonder about that Moorish king who slept over a pool of mercury. How did he feel as the months of

wore on?

Some alchemists must have reasoned unique among metals for its yellow color; added

to

mercury

usual in that, unlike other earths, terious blue flame

seemed easy to

therefore,

(itself silvery in color) is

obvious candidate for a yellow "earth"

It

further that gold

it

is

was

what must be

a yellow "earth."

The

sulfur. Sulfur was un-

could burn, producing a mys-

and an even more mysterious choking odor.

seize

on the idea that mercury and

sulfur repre-

sented the principles of metallicity and inflammability respectively.

The combination

of the

two would therefore put

fire

and

THE SOLAR SYSTEM AND BACK

172

mercury and turn

solidity into

from a

it

silvery liquid to a

golden

solid.

To be

sure,

mercury and sulfur did combine— to form cinnabar.

This was a perfectly ordinary red "earth," nothing the dullness of fact was

rarely

but

like gold,

allowed to spoil the glorious

alchemical vision.

These medieval theories slowly died eenth century, when

During that century, the

fancy.

principle received a cruel it

would have to be

The

in the course of the eight-

chemistry passed through

real

role of

lusty in-

its

mercury as a metallic

knock on the head. As such a principle but was

a perpetual liquid,

it?

year 1759 was a very cold one in St. Petersburg, Russia, and

on Christmas day there was a blizzard and the mercury sank very low

in

the thermometers.

Lomonosov

silievich

tried

The Russian chemist Mikhail Vasto get the temperature to

drop

still

lower by packing the thermometer in a mixture of nitric acid and

The mercury column dropped no lower. It had frozen! The world, snow.

— 39

to

C. and would drop

for the first time,

saw

solid

mercury, a metal like other metals.

By

that time, though, mercury had gained a

outweighed

its false

value was based

A

This

role as a metallic principle. In a way, this

upon

is

its

density,

which

new

13.6 times that of water.

is

13^

pounds.

an amazingly high density. Not only would

in mercury, lead

a liquid; too

would do

much

it

Somehow we

is

is

with water. Thus, when

brought face to face with his

it

up and put

and automatically

gives

it

it

somewhere, he

the kind of

give a jug of water of corresponding size.

And

cury acts as though

table.

it

steel float

don't expect this of

he can be spectacularly astonished.

asked, casually, to pick

hand around

so.

of our experience

young chemistry student

sizable jug of mercury, is

value that far

pint of water weighs roughly a pound; a pint of mercury would

weigh about

a

new

were nailed to the

lift

first

If

he

puts his

he would

of course the mer-

THE SEVENTH METAL

173

made

In 1643, the Italian physicist Evangelista Torricelli of mercury's density.

He

pump

a

level.

could only

He

lift

was puzzling over the problem that a

column

of water 34 feet above

reasoned that the actual work

34 feet high exerted a pressure at

its

A

A

known.

liquid

made

much

a clumsy

is

use of mercury, the densest

column of mercury (13.6 times

water) would produce as

full pres-

no higher.

check that more conveniently (a 34-foot column

thing to handle), Torricelli

column

column of water

base equal to the

sure of the air so the water could be raised

natural

its

of raising that

was done by the pressure of the atmosphere.

To

use

pressure at

dense as

as

base as a column

its

of water 13.6 times as high. If 34 feet of water balanced the total

then 2.5 feet (or 30 inches) would also balance

air pressure,

Torricelli therefore filled a yard-long tube

upended

bowl of mercury. The mercury began pouring out,

in a

it

but only so

far.

to 30 inches,

it

When

the height of the column had decreased

then stayed put, balanced by the

had demonstrated cury entered a

his point

new

and had invented the barometer. Mer-

if

the

air

at Earth's surface,

were as dense

we could

of the atmosphere would be.

the surface

air.

10,560 times

grows

numerous

instru-

its

air,

less

all

the

easily calculate

Mercury

is

way upward

as

what the height

10,560 times as dense as

Therefore, a column of mercury would balance

own

height of

mercury would balance

The

Torricelli

science.

Incidentally, it is

air.

career as a unique substance (a very dense,

electricity-conducting liquid) adapted to use in

ments of

it.

with mercury and

however,

dense as

is

we

5

air.

miles of

This means that 30 inches of air.

not evenly dense rise

and therefore

all

the

bellies

way upward. upward

It

to great

heights.

Of est

all

the metals

melting point.

nary temperatures.

known

It

to the ancients,

mercury had the low-

was the only metal to remain liquid at

ordi-

4

THE SOLAR SYSTEM AND BACK

174

Since ancient times, chemists have discovered dozens of metals, but cury. It

new

none can shake the record low melting point of mer-

was and remains champion.

A

number

of the metals dis-

covered in modern times, however, melt at the temperature of

melting lead or

less.

Here

in

Table 36

is

the

list:

Table 36 Metal

Melting Point

-39 +28

Mercury Cesium Gallium Rubidium

30 38 62

Potassium

Sodium Indium

97 156

Lithium Tin Bismuth Thallium

186

232 271 302

Cadmium

321

Terbium Lead

3 27 327

There you are— the fourteen lowest-melting metals. Five of the eight lowest are the "alkali metals," which, in order of increasing

atomic weight, are lithium, sodium, potassium, rubidium, and cesium. Notice that the melting points are 186, 97, 62, 38, and 28 respectively.

The

melting point goes

down

as the

atomic weight

goes up.

The melting

point of cesium

(for stable metals

F. This

to 82

of a

cury

day

summer

A

second only to that of mercury

temperature of 28

means that cesium would be

day's heat,

and cesium

Could we play with cesium hot enough?

is.

is

anyway).

is

as

is

C.

is

equivalent

liquid at the height

twice as

common

as mer-

we play with mercury

if

the

THE SEVENTH METAL Not

the alkali metals are extremely active and

likely. All

act violently with,

come will

in contact

among

with the perspiration film on your hands and you alkali

increasing atomic weight, cesium

No

There still

is

metals grow more active with the worst of the lot that I've

playing with cesium!

is

a sixth alkali metal, francium, with an atomic weight

higher than that of cesium.

It

its

not known.

would be

It

and the

C. (73

New

be liquid through most of a

However, combine

chemical prop-

and

F.)

would

it

York summer.

chemical activity with

its

fact that only a

its

safe to predict, however, that

melting point would be about 23

therefore

been

radioactive, has only

is

prepared in excessively minute quantities, and erties are

re-

other things, water. Let the alkali metals

be sorry indeed. Since the

listed.

175

its

radioactivity,

few atoms at a time can be brought

to-

gether—and forget francium. Metals can be mixed to form erally

and such mixed metals gen-

alloys,

have a lower melting point than any of the pure metals

making

it

up.

Suppose, for instance, parts of lead, solidify.

The

1

of tin,

result

is

we melt and

1

of

together 4 parts of bismuth, 2

cadmium, and

of the alloy melts at a temperature lower than 23

melts at 71 ° C.

It is a "fusible alloy,"

and tin low as 60 ° C.

is

the mixture

raised slightly, will

2 °

C,

the alloy

one that melts below the

boiling point of water. Lipowitz's alloy, in of lead

let

"Wood's metal." While no component metal

which the proportion

melt at temperatures as

Fusible alloys have their chief uses as safety plugs in boilers or

automatic sprinklers.

The

recipe can

be adjusted to give them a

melting point slightly above the boiling point of water. high

rise in

from the

A

too-

temperature melts them and allows steam to escape

boiler, relieving

dangerous pressure, or allows water to

pass through the automatic sprinklers.

Fusible alloys are also used in practical jokes.

A

teaspoon

made

THE SOLAR SYSTEM AND BACK

176

Wood's metal

of his

is

passed to someone

who then

innocently

hot coffee while carrying on an animated conversation.

connoisseurs of such things, the look on the victim's face finds himself holding the is

mere stub

stirs

To

when he

of the handle of the spoon,

supposed to be delectable indeed.

You can

also

form

alloys of the alkali metals

at lower temperatures than will, in

some

cases,

any

alkali

which would melt

metal alone— and which

melt at temperatures lower, even, than that of

mercury.

But suppose we confine ourselves with impunity.

The

alkali

to solid metals

we can handle

metals and their alloys cannot be

touched. Neither can solid mercury, which

is

too cold for comfort.

Let us ask what metals among those that can be touched are most easily melted.

There are the

fusible alloys of

melting than any of them

and melting

And now its

at only 30

that

I

have

is

which

I've just spoken,

gallium— a pure metal,

but lower

safe to touch,

C. finally

story— in the next chapter.

reached

it, I

intend to go on with

13

I

THE PREDICTED METAL

frequently receive letters from readers

some kind

facts into

of pattern.

who attempt

to find

some

by

shuffling facts or supposed

Very

often, the readers are not

insight into the mysteries of nature

professionals or experts in the subject they are trying to handle.

My own but

I

impulse, then,

never quite dare.

even when

I

is

to reject such attempts out of

invariably

all,

peculiar horror against going

man who

is

Reina Newlands, and if I

all

wrong,

one can never

down

I

try to

tell;

make my

and

I

have a the

in scientific history as

laughed at So-and-So.

For instance, there

him

ponder before answering, and

decide they are

I finally

response a polite one. After

hand-

only

knew

I

his

Newlands was born

the

man who

laughed at John Alexander

would gladly point the

finger of scorn at

name.

in 1837 of

an English father and an

Italian

mother, and he remembered his Italian ancestry well enough to fight

with Garibaldi in i860 for the unification of

interested in both chemistry

Italy.

He

was

and music, and eventually became

an industrial chemist specializing

in sugar refining. In his spare

moments, he turned

from sugar

his attention

to the elements.

THE SOLAR SYSTEM AND BACK

178

One had

to

wonder about the elements

sixty different

elements were

sorts,

and

There seemed no

no

order.

varieties.

in those days.

known— elements

about

logic to the

of

list,

By all

1864, kinds,

however,

There seemed no way of predicting how many elements

there might be altogether

the number might be

and

infinite.

all

in 1864,

Chemists were growing more and

more depressed over the matter. elements of

anyone could say

for all

there were vast

If

numbers of

would be unbearably com-

kinds, the universe

plicated. It is

almost an article of faith with scientists that the universe

orderly and, basically, simple. Therefore, there

had

to be

is

some

way of finding order and simplicity in the list of elements. But how? Newlands amused himself by juggling the elements in various ways. Over the past few decades, chemists had been carefully working out the atomic weights of the elements (that tive

is,

the

masses of their respective atoms), and those figures

seemed hard and reasonably accurate.

Why

rela-

now

not, then, arrange the

elements in the order of atomic weight?

Newlands did

so,

then

listed

them

in a table seven elements in

width. First, there were the seven elements of lowest atomic weight; then, under them, the next seven, and so on. It seemed to

Newlands that

certain groups of elements of very similar prop-

erties fell in vertical lines

when

this

was done, and that

this

was

significant.

Could

it

be that elemental properties repeated themselves

groups of seven? His musical interests led him

member

in

irresistibly to re-

that the notes of the scale repeated themselves in groups

of seven.

The

the

Musical notes repeated themselves in octaves, in other

first.

eighth note ("octave") was almost a duplicate of

words. Might not the same be true of the elements?

Newlands therefore wrote up his results in a paper presented Chemical Society and referred to

for publication to the English his discovery as the

"Law

of Octaves."

THE PREDICTED METAL The might

mine

society rejected

179

with contempt, very

it

much

for similar publication.

jection, though, for

had

it

They had some

they

as

had submitted one of these speculative science

if I

essays of

reason for the

re-

to be admitted that Newlands's table

was quite imperfect. Although some very similar elements

into

fell

columns, some extraordinarily dissimilar elements did the same.

However, what

really

bothered the society,

I

am

sure,

was the

whole notion of playing games with elements and making tabular arrangements.

The

very notion of listing the elements in order of

atomic weight seemed a wise guy

why he see

I

trivial trick,

and one chemist

(this

referred to at the start of the essay) asked

didn't try to

what kind of a

list

the

is

Newlands

the elements in alphabetical order and

table he could squeeze out of that.

I

only hope

the gentleman lived long enough to have to swallow his words. It

would only have taken eleven Actually,

a

two years

earlier

years.

(and quite unknown to Newlands)

French geologist with the formidable name of Alexandre Emile

Beguyer de Chancourtois had also

tried to list the

elements in

order of atomic weight. Instead of making a table, he imagined

the ner,

list

of elements

wound

helically

he got much the same

table,

results

about a cylinder. In

man-

this

Newlands had obtained

in his

but in nowhere nearly as simple a manner.

Beguyer wrote a paper on the subject and included a painstaking diagram of what his cylinder of elements would look

like.

The

paper was published in 1862 but the complicated diagram was omitted.

The

omission of the diagram

to follow. This

was

all

made

the article impossible

the more so since Beguyer de Chancourtois

was a poor writer who made

free use of geological terms that

were

unfamiliar to chemists. His paper was completely ignored.

Despite the dangerous possibility of being laughed

at,

chemists

continued, occasionally, to try to wring order out of the elements. As the

list

of

1860s closed, two men, independently, each

THE SOLAR SYSTEM AND BACK

l80

One was

a German named Julius Lothar Meyer and named Dmitri Ivanovich Mendeleev. Matters had grown more subtle in the five years since Newlands. Both the German and the Russian arranged elements in

made

a try.

the other a Russian

order of atomic weight, but both used other atomic properties as

Without going

additional guides.

into detail here,

I

can say that

Meyer made use of atomic volume and Mendeleev used valence. Each man noted that when the elements were arranged in order of atomic weight, the other properties (such as atomic volume and valence) rose and fell in an orderly manner. They recognized further that the period of rise

and

same number of elements. At the seven elements long, but later lands's errors that able,

he

tried to

and that helped make

would

fall

into the

it

fall

did not always involve the

start of the list

grew longer.

make the

It

the period was

was one of New-

length of the period invari-

inevitable that dissimilar elements

it

same column.

Both Meyer and Mendeleev succeeded

Mendeleev managed

to get into print

in publishing their work. first,

One might

while Meyer published in 1870.

publishing in 1869,

expect that Mendeleev,

a Russian, would lose out even so because, in general, European

chemists did not read Russian, and Russian discoveries were usually

ignored in consequence. However, Mendeleev was foresighted

enough to publish

Even credit,

so,

were

in

German.

Mendeleev and Meyer might it

still

have received joint

not for the difference in their approaches. Meyer

was timid. Not

at all eager to

compromise

his scientific career

by

stepping out too far ahead of the front lines, he advanced his conclusions in the form of a graph relating atomic volume to

atomic weight.

He made

graph speak for

itself,

no attempt

which

it

at interpretation,

but

let

the

did but softly.

Mendeleev, however, actually prepared a "periodic table of the elements" as Newlands had done, one in which the various properties varied in a periodic

manner. Unlike Newlands, Mendeleev

refused to allow any of the columns to contain unfitting ele-

THE PREDICTED METAL ments. didn't

If fit,

an element seemed about to

Mendeleev moved

it

fall

into a

l8l

column which

to the next column, leaving

it

behind

an empty hole.

How that

it

explain the

empty hole? Mendeleev pointed out boldly

was quite obvious that not

all

elements had yet been

dis-

covered and the empty hole contained one of these undiscovered elements. Newlands had

made no allowance

undiscovered

for

elements. As for Meyer, his graph was so arranged that "holes"

did not stand out, and

Meyer himself

later

admitted he would

never have had the courage to argue as Mendeleev had done.

From

the properties of the remaining elements in the column

with the empty hole, Mendeleev went on to

insist

he could even

predict the properties of the undiscovered elements. in particular, the holes that

He

selected,

were under the elements aluminum,

boron, and silicon in his early tables. These holes, he said, contained undiscovered elements which he provisionally

aluminum," "eka-boron," and

(Eka the

is

"first

Sanskrit

named

"eka-silicon" respectively.

the Sanskrit word for "one" so that the

name

implies

element under aluminum" and so on. Since dvi

word

for "two," the

I

know

is

the

two holes under manganese would

be "eka-manganese" and "dvi-manganese" the only cases

"eka-

respectively.

These are

of where Sanskrit has been used in scientific

terminology.)

Consider eka-aluminum, for instance. Judging from the the column and from

decided that

its

its

position in the

list

generally,

atomic weight would be about 68; that

have a moderate density of

rest of

Mendeleev

5.9 times that of water; that

it

would

it

would

have a low melting point but a high boiling point; and that

would have

The

it

a variety of carefully specified chemical properties.

rest of

the chemical world reacted to this with anything

from a laugh of indulgent amusement to a snort of contempt. Playing with elements, and building complicated structures out of them, was bad enough, but describing elements one had never

THE SOLAR SYSTEM AND BACK

l82

seen on the basis of such structures seemed like nothing

more

than mysticism—or even charlatanry.

Mendeleev might not have been saved from worse fact that he was Russian. Westerners must have felt indulgent toward the ravings of mystical Russians, and tolerated there what they would not have tolerated among their own I

wonder

criticism

if

by the

countrymen.

But

the focus to France again and to another French-

let's shift

man with a formidable name—Paul Emile Lecoq He was a self-educated young man of means,

de Boisbaudran. fascinated with

chemical analysis, and particularly attracted by the new technique of spectroscopic analysis in to

which heated minerals could be made

produce spectra composed of

Each element produced

its

lines of differently colored light.

own

spectral lines distinct to itself.

This technique had been introduced in 1859 an d

had almost

at

its

once found minerals yielding spectral

developers lines

not

produced by any known elements. Orthodox chemical investigation into the minerals producing these lines demonstrated the

existence of two

new

elements: cesium and rubidium.

Lecoq de Boisbaudran burned to discover elements, too, and moving into the field at the first announcement, he spent fifteen years subjecting every mineral

troscopic analysis.

and moved

his

hands on to spec-

carefully considered the lines

he obtained

intelligently in the direction of those minerals

him

most

new elements he wanted. he chanced upon a mineral which had been known

apt to give Finally

He

he could get

the

early mineralogists as galena inanis or "useless lead ore." It useless because

it

was a mixture of zinc

sulfide

and procedures designed to get out the lead naturally failed. It

is

now

called "sphalerite"

meaning "treacherous" because

it

so

and it

from

to

was

iron sulfide

didn't contain a

Greek word

often deceived the early

miners.

This ore was anything but useless or treacherous to Lecoq de Boisbaudran, however. In February, 1874, he subjected the min-

THE PREDICTED METAL and spotted two

eral to spectroscopic analysis

183

he had never

lines

seen before.

He

hastened to Paris where he repeated his experiments before

important chemists and established his

priority.

He

then began

working with larger quantities of the mineral and by November, 1875,

worked

some

to the

on the

tests

it down to a gram of a new metal, enough to present Academy of Sciences in Paris and to run chemical

rest.

The new metal proved had a density of

70. It

point of 30

showed a

C,

to

have an atomic weight

just

under

5.94 times that of water, a low melting

C, and

a high boiling point of nearly 2000

it

variety of specific chemical reactions.

This had no sooner been announced when Mendeleev, far

away

pointed out excitedly that what Lecoq de Bois-

in Russia,

baudran was describing was precisely the eka-aluminum that he

had deduced from

The

his periodic table five years before.

chemical world was thunderstruck. Mendeleev's predic-

tion of the properties of

eka-aluminum existed

in print.

The two

existed in print.

There was no denying riodic table ity

had

tallied it.

Lecoq de

new element

Boisbaudran's description of the properties of his

almost exactly in every detail.*

Mendeleev had

to

be

right.

to be a useful description of the order

and

The

pe-

simplic-

behind the elements.

If there

was any doubt, the other two elements described by

Mendeleev were fallen

credit

death, just

found within a few years and predictions

also

with the fact. As all the ridicule had on Mendeleev before and none on Meyer, so now all the went to Mendeleev. In 1906, just a few months before his

were again found to

tally

Mendeleev almost received the Nobel

one vote to Moissan, the discoverer of

Prize, losing out

by

fluorine.

* Lecoq de Boisbaudran first got a figure of 4.7 for the density, but Mendeleev insisted that that could not be so. And he was right. The Frenchman's first samples were too impure. After proper purification, the density figure matched the prediction. discrepancy in which the prediction won out over the first observation made the situation even more dramatic.

A

THE SOLAR SYSTEM AND BACK

184

Both Newlands and Beguyer de Chancourtois

to

lived

see

themselves vindicated. After Beguyer de Chancourtois died in 1886, a French journal, in remorse, published his diagram of the

one that had not been published

cylinder, the

And

Royal Society

in 1887, the

paper which the Chemical Society had refused to publish.

for the

As

for the

element discovered by Lecoq de Boisbaudran, he took

the privilege of the discoverer and

named

ism, he

Rome and

it

Yet was

used the Latin

name

For

Out

it.

this

of noble patriot-

he turned

to ancient

Gallia ("Gaul" in English), so

"gallium."

patriotism, pure

it

named

for his native land.

new element became

that the

is

thirty years before.

gave Newlands a medal

finally

and unalloyed? Lecoq

"the cock," and that noble barnyard fowl

is

in English

gallus in Latin.

Well, then, was gallium named for Gallia, the nation, or for the discoverer himself?

Gallium hand,

is

it isn't

common

Who

common uncommon

not an extremely

element, but on the other

a particularly

one, either. It

as lead,

which makes

it

about

mercury and three thousand times gallium

nately,

much more

is

earth's crust than

make

Its richest

the ore

is

its

as

thirty times as

common

is

about as

common

as

as gold. Unfortu-

evenly spread out through the

any of these other elements, so that there are

few places indeed where tion to

gallus,

can say?

it

can be found in

sufficient concentra-

extraction practical.

source

is

a

mine

in

Southwest Africa and even there

only about 0.8 per cent gallium (as compared, though,

with a usual figure of 0.01 per cent). Several thousand pounds of

metal are

all

The most which

is

usually,

that

will

melting point

body (37

produced in the course of a

spectacular property of gallium

29.75

but

is

is

is

year.

its

melting point,

C. (or 85.55 F.). This means that it is solid melt on a hot summer day. Notice, too, that its

below the normal temperature of the

C. or 98.6

dramatic experiment.

F.). This

makes

it

human

possible to perform a

THE PREDICTED METAL You

185

begin with a rod of solid gallium. That's a moderately ex-

pensive proposition right there, for the present cost of gallium is

something

like

$50 an ounce.

Oh

you borrow a rod of

well,

solid gallium.

when

Naturally, you choose a day

and you hold the rod

seventies

the end of the gallium rod leave

it

down

into the

is

in the

Now

bring

palm of your hand and

there.

Slowly, the

The

the temperature

in a pair of cool tongs.

warmth

of your

hand

melt the gallium.

suffices to

rod shrinks, and gathering in your palm will be a puddle of a

silvery liquid that looks like

produce

and

this effect

it

that looks like steel puddle

Liquid gallium

is

No

mercury.

other pure metal will

quite creepy to watch something

is

up

in that

manner.

perfectly safe to hold, but

dense as mercury so

it

is less

than half as

doesn't have the latter element's unusual

weight. Furthermore, liquid gallium wets glass as mercury does not,

which deprives the former of some interesting

The

melting point of gallium can be lowered

still

effects.

further

if it is

mixed with other comparatively low-melting metals. With the proper admixture of indium and as

low as 10.8

tin,

an alloy with a melting point

C. (51.4° F.) can be produced.

It

can replace mer-

cury for frictionless electric contacts with moving parts.

Once if it is

gallium melts,

cooled quite a

However,

it

freezes again only with reluctance, even

a piece of solid gallium

if

even in an ice bath.

bit. It will stay liquid is

dropped into such "super-

cooled" liquid gallium, the solid acts as a "seed" about which the gallium atoms line up in orderly fashion, so that the liquid fies

solidi-

at once.

In the case of most substances, the liquid form

more voluminous than the ally shrinks

when

solid form.

it solidifies.

There are

A

dense and

liquid therefore gener-

several exceptions to this,

however, and the most important of them

Where

is less

liquid water has a density of 1.00

is

water.

gram per cubic

centi-

meter, ice has a density of 0.92 gram per cubic centimeter. This

THE SOLAR SYSTEM AND BACK

l86

means that 10 cubic inches of 11 cubic inches of ice.

The

back to 10 cubic inches

is

in

a

closely

fitting

enormous.

If

water

container,

sealed

must be exerted on the

ice to

keep

it

is

allowed to freeze

enormous pressure

that

from expanding. There are

few containers that can do so and even strong ones

Gallium

is

another exception.

The

means that 29 cubic inches of

The

as in the case of water,

gallium

is

will shatter.

density of the liquid

grams per cubic centimeter, while that of the cubic inches of solid.

form

liquid water will freeze to

pressure required to shrink that ice

solid

is

is

6.1

This

5.9.

liquid gallium will freeze to 30

pressures developed are not as

enormous

but they are large enough. For that reason,

shipped in flexible containers of rubber or

in the course of shipping, the metal melts

and

plastic. If,

resolidifies,

the

containers bulge and distort rather than break.

Gallium

is

remarkable not only for

its

low melting point, but

also for its high boiling point. It boils at 1983 °

nary temperatures, or even at a red heat, quantities of vapor. In this

which

boils at 357

it

is

it

C. so that at ordi-

produces insignificant

quite different from mercury,

C. and which produces sizable amounts of

vapor even at ordinary temperatures. Mercury vapor

is

toxic

which means that the metal should be handled with considerable care.

at

Gallium, on the other hand, poses no problems of that sort

all.

This combination of low melting point and high boiling point

on the part of gallium

Mercury

is

raises a point.

used in thermometers because

it is

liquid throughout

the ordinary range of temperatures in which chemists are interested.

To

record temperatures below

— 39

C. chemists have to

use alcohol thermometers, for ethyl alcohol doesn't freeze

temperature of

— 117

C.

is

reached. For temperatures lower

till

a

still,

other dodges are used.

What

about temperatures in the ranges higher than a mercury

thermometer can handle? For that we need some substance that will

not change with heat (an element

is

safer

than a compound

THE PREDICTED METAL in this respect), that will

187

be liquid through part of the liquid

range of mercury and that will remain liquid at temperatures as

high as possible. In other words, what elements have melting points lower than

C. and boiling points higher than 357 C? There are exactly fourteen of them and I am going to arrange them in Table 37 in 357

order of decreasing length of temperature range over which they

remain liquid:

Table 37 Element

Melting Point (° C.)

Tin Gallium Indium Lead Bismuth Thallium Lithium Sodium

(degrees)

2270

2038

30

1983

156

2000

1953 1844

327 271

1560

1620

1293 1289

ii55

1457 1336 880

98 62

Rubidium Cesium

Range

232

302 186

Potassium

Liquid

Boiling

Point (° C.)

1150 782

700

698 662

670 688

642 47i

760

38 28

Selenium

217

Cadmium

321

767

446

Sulfur

113

445

332

As you

the elements listed have a liquid range

see, three of

nearly or quite 2000 degrees. This

no others sure, a

like it in

number

the entire

list

very unusual, for there are

of elements that remain liquid for 2000 degrees

and more, but that have

their liquid range in a very high

convenient spread of temperature. liquid for 2600 degrees useless.)

is

of elements. (There are, to be

from 2700

Osmium,

and

in-

for instance, remains

C. to 5300

C. That's pretty

THE SOLAR SYSTEM AND BACK

l88

For the "high, but useful" range, which would take us up to

C, we

2000

indium

As

have

just

the three elements:

tin,

gallium,

happens, none are elements that are available in large

it

quantity, but then large quantities are not needed for

Of

eters.

the three, gallium

far the easiest to filling

and

in that order.

is

thermom-

the lowest melting and therefore

handle in a technique that must use liquid in

the thermometer.

For that reason, gallium thermometers have indeed been used.

As the

column of mercury is enclosed by glass in the ordinary thermometer, so the fine column of liquid gallium is enclosed by fine

quartz in the gallium thermometer. Such gallium thermometers are particularly useful in the range

Gallium

is

from 6oo°

proving to be useful in

all sorts

which purpose

One

of

it

C.

of solid-state devices,

must be prepared (and concentrations of not more than one part in a for

to 1500

is)

with impurity

million.

compounds, gallium arsenide (GaAs), can be used

its

in

solar cells, converting sunlight directly into electrical current. It

can be used as a semiconductor and in transistors at temperatures

beyond those work. There laser

at

is

which more ordinary devices of that

every reason to think

it

sort will

can be used to produce a

beam.

There

no doubt but that gallium can make

is

splash in the

pens to

it is

manner

of

new world

likely to

its

a satisfactory

of far-out science, but nothing that hap-

outweigh the glamour and significance of the

discovery.

BIOLOGY

THE TERRIBLE LIZARDS

14

James D. Watson has recently published a book, The Double

which he

Helix, in

structure of the lines

details the inside story of the discovery of the

DNA

molecule.

The book

is

making the head-

not because of the importance of the subject but because of

the fact that

human Well,

it

exposes scientists as

human

failings.

why

not?

A

great intellect need not necessarily

panied by a great soul. There are

villains

among any other group. My own pet candidate for a high place Sir Richard Owen, a nineteenth-century was the

last of

These believed

in evolutionary

nal forces that drove creatures

When,

in

Species, in selection, it,

among

1859,

English zoologist.

who had

naturalist

horrified.

force,

is

He

taken

Lorenz Oken.

development through vague

Charles Darwin published

was a blind

as

inter-

on to some particular end.

which he presented evidence

Owen was

be accom-

scientists

in scientific villainy

the top-rank "nature philosophers"

up the mystical notion of the German

scribed

beings possessed of

The

for evolution

Origin

of

by natural

Natural selection, as Darwin de-

changing species through

on random variations among individuals.

its

action

THE SOLAR SYSTEM AND BACK

192

Owen

could not accept evolution by random effects and he

came out even his

against Darwin. That, of course, was his right. It was scientific

suggestion,

like

duty to disagree with scientific

all

battles fought in the intellectual arena,

was outlawed in such

No He

Owen

many

make those

chose to

tensively

and no honorable weapon

chose to review Darwin's Ori-

he could wangle.

different outlets as

reviews anonymously and to quote ex-

like a

He

crowd.

of the contents of the

own

his

book and

urged others to denounce Darwin,

to ridicule

vitriolically

them the

before lay audiences, feeding

work,

chose to give an unfair it

than to present opposing testimony objectively. Worst of

ically,

the

survive

to

and with worshipful approval from

making himself sound

summary

had

battles.

honorable weapon.

gin of Species in as

might. Darwin's

all his

suggestions,

and

rather all,

he

unscientif-

necessary misin-

formation for the purpose. In short, it is

Owen was

cowardly, spiteful, and contemptible, and

a source of gratification to

me

that he lost out.

Yet that can't be allowed to obscure the portant contributions to biology.

He

fact that

he made im-

discovered the parathyroid

glands in 1852, while dissecting a rhinoceros. (It was to be quite

some first

years before they were found in

to describe the recently extinct

man

moas

as well.)

of

New

He

was the

Zealand and

the anything but extinct (alas!) parasite that was later found to

be the cause of

trichinosis.

His greatest fame to the general public, however, word.

He

was one of the

earliest of

those

who

lies in

a single

studied the

fossils

of certain giant creatures, long since extinct, which soon caught

the imagination of the world. Weighing up to five times the size of the largest living elephant, they shook the ground between

70,000,000 and 270,000,000 years ago.

The huge

skeletons that were built

up out of the

nants were clearly reptilian in nature, so rible lizards,"

Owen

fossilized

rem-

them

"ter-

called

and since he used Greek, that became "Dinosauria."

THE TERRIBLE LIZARDS

193

more

closely related to

(Actually, those ancient giant reptiles are alligators

than to

lizards,

but

I

must admit that "Dinocrocodilia"

would have been a rotten name.)

The name caught

on,

and today,

am

I

sure,

many American

children can describe various dinosaurs even though they can't describe a hippopotamus

Yet

for all the

is

term

is

it

for all its continuing pop-

has passed out of the scientific picture. As

ularity, it

there

and never even heard of an okapi.

fame of the word, and

no

single

group of animals

we can

gone from the chart of animal

call

it

turns out,

by that name. The

classification.

You can

look

over from top to bottom and you will find nothing labeled

"Dinosauria." (Ha, ha, for you, Sir Richard Owen.)

Furthermore, dinosaurs are not necessarily large and monstrous.

Many

of

them were quite small and were considerably less an angry police dog. Then, too, some of the

rible" than, say,

"ter-

large

extinct reptiles that look terrible indeed are not considered dinosaurs in the strictest sense of the word.

So let's go into the matter of the terrible lizards and find out what they are and what they are not. In classifying ancient reptiles one must, of necessity, use bone structure as the source of distinctions, for

these long-dead creatures that

used quite often, because

it

we have

it is

only the bones of

left to study.

The

skull

has a complicated structure of

is

many

bones, and this structure appears in convenient broad variations.

For instance, the

class "Reptilia"

is

divided into

six subclasses

in accordance, to a large extent, with the structure of the skull.

The most

primitive skulls have the

bony

structure behind the

eye socket solidly enclosed. Such a skull belongs to the subclass

Anapsida ("no opening").* Greek apsis means "wheel/* "arch," "vault," and a few other meaning of "wheel," and consider that it might be applied to a roughly circular opening, we might as well translate the word as "opening" and make it clear. In this article, I will try to give the literal meanings of the zoological terms, which are almost always in Greek or Latin, of course. I must not conceal from you that I don't always know why those literal meanings have been chosen. If any Gentle Reader knows, I will welcome the * Actually, the

things. If

we

information.

take the

THE SOLAR SYSTEM AND BACK

194

The

earliest

skulls.

important

the order Cotylosauria ("cup-

reptiles, of

because of their cup-shaped vertebrae), had anapsid

lizards,"

These

feet long,

more than

cotylosaurs, low-slung, stocky, not

and not

terribly

forebears, existed about

advanced over

far

They

from which

all

forms branched off—

later

though the cotylosaurs themselves are long since

One

group of their descendants,

are often

stem of the

called the "stem-reptiles" since they represent the reptile family tree,

amphibian

their

300,000,000 years ago.

six

extinct.

who appeared

early (perhaps

230,000,000 years ago), and only one, retained the anapsid skull.

Oddly enough,

this primitive order

although more ad-

still exists,

vanced cousins have long since grown

This

extinct.

is

Chelonia ("turtle"), which, of course, includes the

the order

turtles

and

tortoises.

Another type of

reptilian skull has

socket. Creatures with such skulls sida

an opening behind the eye

make up

the suborder Synap-

("with opening"). This entire suborder

there are

no

living reptiles with synapsid

scended from these Synapsida are the

There are two other kinds of ing behind the eye sockets.

is

extinct; at least,

skulls.

mammals

However, de-

of today.

reptilian skulls with a single open-

The arrangement

of the bones around

that opening differ in the two cases, and both differ from the

arrangement in the synapsid Parapsida

("side opening")

Both of these suborders are reptiles

skulls.

So we have the suborders

and Euryapsida ("wide opening"). totally extinct.

with either paraptid or euryaptid

There are no

skulls.

living

Nor have any

non-reptilian forms been descended from them.

The most

familiar

("fish-lizards").

This

is

of

the

a good

parapsids

are

name because

appearance, 220,000,000 years ago or

so,

the

Ichthyosauria

at their

first

known

they had already been

become completely adapted to it. They had assumed the streamlined fish-shape just as some of our modern sea mammals have. In fact, they very closely resemble living in the sea so long as to

long-snouted dolphins.

THE TERRIBLE LIZARDS Of

course,

when we speak

195

we

of ichthyosaurs,

don't speak of a

particular animal, but of a large group of diverse animals.

There

were species of ichthyosaurs that were no more than 2 feet long, instance,

and other

largest ichthyosaurs

and were, mals

species

which reached lengths of 60

were the

size

feet.

for

The

modern sperm whale

of the

in their time (180,000,000 years ago), the largest ani-

alive.

By

40,000,000 years

the giant species had died

later,

out and considerably smaller species, with shorter

tails

and no

teeth, took their place.

We arrive now at a tricky point. The ichthyosaurs, outward

fishlike

appearance, are complete and

despite their

thoroughgoing

They are quite extinct and some of them were enormous. Does not this qualify them— as large, extinct reptiles— to be considered among the dinosaurs? reptiles.

In popular speech, they surely are, but to purists this proper. Almost

all

long to a particular subclass of Reptilia, and Parapsida Strictly speaking, creatures outside that

on the term and

is

not

the creatures popularly called dinosaurs beis

not

it.

one subclass have no claim

in that sense the ichthyosaurs are not dinosaurs.

Passing on to Euryapsida,

we have

other aquatic creatures only slightly

as the

best-known examples

less well

adapted for sea

life

than the ichthyosaurs. All have limbs adapted for paddling and

swimming. Some look land, but clearly

one group

though they can

so completely paddle-equipped

cannot leave the

lizards,"

hobble around on

as is

sea.

still

These are the Plesiosauria

because they looked pretty

much

that

it

("near-

like reptiles except for

the oddity of four paddles in place of ordinary limbs). If

the ichthyosaurs were the reptilian equivalent of whales and

dolphins, the plesiosaurs seem to be reptilian seals. Their most re-

markable attribute, perhaps, were the long necks possessed by

most (but not

all) of

them. These were probably sent darting

ward, like animated spears, after

fish.

for-

At the height of the age

of reptiles, 100,000,000 years ago, certain varieties were 50 feet

long or more, with necks making up two-thirds of this total

THE SOLAR SYSTEM AND BACK

196

One

length.

of these gigantic varieties, the Elasmosaurus ("plated

lizard"), probably

The

had the longest neck ever

plesiosaurs look

dinosaur than

the

long necks and

tails,

much more

ichthyosaurs

and

They have

do.

And

a barrel-like body.

on Earth.

existing

like the ordinary

notion of the small

heads,

yet the plesio-

saurs are not dinosaurs because they, too, like the ichthyosaurs,

belong to the wrong subclass.

That brings

us to a fifth kind of reptilian skull. In a purely rep-

tilian sense, that fifth is

the most successful by

far. (I

qualify the

statement because the synapsids, although only moderately successful as reptiles, did give rise to the

be considered an enormous,

mammals, and that must

non-reptilian, success.)

if

In this last kind of skull, there are two openings behind the

eye socket; such a skull

There

a "diapsid"

is

son for that

that there are

is

no

of reptiles with diapsid skulls session of the

The

rea-

than two important groups

and neither can claim

sole pos-

title.

of the diapsid

Lepidosauria

("scaled ("scaly,"

from Latin), which reptiles,

less

skull.

The

from Greek). This includes the order, Squamata

first

lizards,"

("two openings")

however, no one subclass bearing that name.

is,

subclasses

in turn includes the

is

most

successful of living

the snakes and lizards.

Another order of lepidosaurs, Rhynchocephalia ("snout-heads," because they have prominent, beaky snouts),

is

completely different reason; not because

is

because

gin—a

it

it

interesting for a flourishing,

but

has avoided extinction by the narrowest possible mar-

single rare species.

The

order was never very important

and, except for that one survivor, died out about 70,000,000 years ago.

But there remains that one

lizard-like creature,

snout to

main

tail tip.

In recent times

it

was

still

is

a moderately large

long, at most, to

from

be found on the

New Zealand, but no longer. It is now to be found offshore New Zealand islets, where it is sternly pro-

islands of

only on a few

survivor. It

no more than 30 inches

THE TERRIBLE LIZARDS tected by law. Its tive

common name

197

tuatara ("back-spine," in na-

is

Maori, since in addition to the scales that cover

down

has a line of spines

backbone).

its

sphenodon ("wedge-tooth"), which Despite

looks,

its

it is

not a

that no lizard possesses (the

is

lizard. It first

Its

the

body,

it

more formal name

is

name

of

its

its

genus.

has a bony arch in

skull

its

giveaway to the early dissectors

that they had something unusual in hand). There teeth are at-

tached in non-lizard-like fashion and

membrane"

which birds

it

also has a "nictitating

possess,

but not

lizards. Fi-

has a particularly well-developed pineal gland at the top of

nally, it its

in its eyes,

brain,

something

lizards

In the young sphenodon,

do not have nearly

a third eye, though there

as well-developed.

bears the anatomical appearance of

it is

no indication

yet that

it

light-

is

sensitive.

The second and to

it is

diapsid subclass

this subclass,

and

is

Archosauria ("ruling reptiles"),

this subclass only, as the

name

implies,

which dinosaurs belong.

Of

we might

course,

out of creatures that

all

why two

have diapsid

skulls.

made

subclasses are

Well, there are other

For one thing, the archosaurs have teeth

distinctions.

sockets

stop to ask

and the lepidosaurs (with one very minor

set

in

exception) don't.

This seems an unimportant distinction to the layman, perhaps, but

it isn't.

The improvement

in tooth efficiency

is

such that the

archosaurs became, for a time, the most successful of tilian

subclasses. Besides,

sentative of a

The most

one such distinction

whole family of

it

is

usually repre-

distinctions.

primitive archosaurs

("socket teeth"), and

is

the rep-

all

make up the

from these that

order Thecodontia

all

other archosaurs

developed, though they themselves are long since extinct.

Many

of the thecodonts were rather

adopted a bipedal posture. The

on the small

side

forelimbs were reduced in

and size,

the hind limbs enlarged and strengthened, and a long balancing tail

was developed. They rather looked

like reptilian kangaroos.

THE SOLAR SYSTEM AND BACK

198

Certain heavier and clumsier thecodonts, however, were forced

on

to remain

which

dilia,

all fours,

and these developed into the order Croco-

The

survives, of course, to this day.

and

alligators

crocodiles are the only living reptiles that belong to the subclass

And

Archosauria, the one to which the dinosaurs belonged. crocodiles are not to

are their closest living relatives.

two

and only two

orders,

gators

and

yet

be considered dinosaurs, even though they

The

dinosaurs are restricted to

The

orders, within the subclass.

crocodiles are outside those

two orders and are

alli-

there-

fore not dinosaurs.

More spectacular which make up the

is

another group of thecodont descendants,

order Pterosauria ("winged lizards"). These

developed long thin webs based on enlarged

were lighter

still,

little fingers,

made wings out

of them,

and were the only

reptiles

ever to engage in true flight.

The long

early pterosaurs

tails,

too.

The

and often lacked teeth

much

ones grew larger, had altogether.

the skies held the largest of

and tails,

all

About 150,000,000

years ago,

the pterosaurs. This was Pterano-

feet and a long-crested skull some 3 feet from end to end. But the pterosaurs were not the only descendants of the the-

don.

had

teeth,

shorter

had long heads with sharp

later

It

a

wing span of about 20

codonts to learn the secret of true verted

its

scales into feathers.

From

flight.

creatures, the birds, so radically different

so

many

Another group con-

these descended a group of

from other

reptiles in

ways, as to deserve being placed in a class of

its

own,

"Aves."

There now remain the two orders of archosaurs (both extinct)

that contain the dinosaurs.

ship to other reptiles,

mainly with zoological

I

To

simplify their relation-

have prepared Figure

classification

and

entirely

is

8,

which deals

not primarily con-

cerned with lines of evolutionary development. If

the two orders could be grouped into one, that combined

order would undoubtedly have retained Owen's

title

of "Dino-

the terrible lizards

199

Figure 8 The Reptiles

ARCHOSAURIA

EURYAPSIDA

(diapsid skulls)

i

V PTEROSAURS

V DINOSAURS

TUATARA

V

TURTLES

SNAKES & LIZARDS

V MAMMALS

sauria."

However, a closer study of the creatures early showed that

there were important distinctions to be

made among them,

no-

tably in the pelvic girdle (or hipbone).

Since the ancestral dinosaurs had the bipedal gait of the thecodonts, the pelvic girdle had to bear the

The

pelvic girdle

full

was strengthened therefore and

bones enlarged in the course of evolution. of the girdle, the ilium, was enlarged

is

characteristic of

its

three chief

The uppermost bone

and came

backbone to produce a structure of great This fusion

weight of the animal.

to

be fused

solidity

both orders and

is

to the

and strength. therefore an

important characteristic mark of the dinosaur.

There are two other bones to the

girdle,

however. In some

dinosaurs these remained well separated and were set nearly at right angles. This rather resembles the situation in living lizards

and

so

all

dinosaurs with this arrangement of hipbones are placed

in the order Saurischia ("lizard-hip").

In the remaining dinosaurs, the two lower bones of the pelvic girdle are lined

up

closely parallel

and

slant backward. This ar-

THE SOLAR SYSTEM AND BACK

200

rangement resembles that

in birds

and

so these are placed in the

order Ornithischia ("bird-hip").

Nor

is

ticeable

anyone

the distinction a petty one in zoological terms. So no-

is it,

that once the difference in hip girdles

whether a dinosaur belongs

at all can tell

explained,

is

to

one group

or the other by one quick glance at the skeleton. It is for this

term.

logical

reason that "dinosaur"

One

can,

is

no longer

a formal zoo-

and often does, speak of "saurischian

dinosaurs" and "ornithischian dinosaurs." It

is

more

appropriate,

however, to speak of "saurischians" and "ornithischians," leaving out the word "dinosaur" altogether.

The

saurischians

had

their

two suborders, Theropoda

heyday

first.

("beast-feet")

These are divided into

and Sauropoda

("lizard-

bones of the former more closely resemble

feet"), because the toe

mammals in number than do the toe bones of the latter. An easier way of distinguishing the two suborders is to remember that the theropods are bipeds and the sauropods are those of

quadrupeds.

The

earliest of

the theropods were, in

thecodonts— light, small bipeds adapted were the Coelurosaurs ("hollow

lizards,"

fact, very

much

because

it

chicken and was the smallest of the

known

However, there was a general tendency

tition

on

among

strength.

wore

of

on—perhaps

size of a

dinosaurs. for species

to

grow

because increasing compe-

the various dinosaurs put an increasing

By

Many

and one, Compsognathus ("elegant jaw"

was so small and delicate), was only about the

larger as the ages

These

because their bones were

hollow for the sake of lightening the body structure). these were quite small,

like the

for fast running.

premium

the late Cretaceous, 80,000,000 years ago, coe-

lurosaurs the size of ostriches

almost exactly the

size

had evolved. One of them was ostrich, with a small head

and shape of an

sporting a horny, toothless beak, a long neck, and powerful legs.

Even though

it

had forearms with clutching

fingers instead of

THE TERRIBLE LIZARDS stubby, vestigial wings, and a long called

tail

201

instead of plumes,

it is still

"Ornithomimus" ("bird-imitator").

Another lizards"),

was

theropods

of

line

so

called

the

"carnosaurs"

So were the coelurosaurs, as a matter of

eating.

("meat-

because they were characteristically meat-

physical appearance of the carnosaurs

made

but the

fact,

much more

the fact

horribly evident in their case.

The

carnosaurs retained the bipedal structure but went in for

beyond anything the coelurosaurs could do. By the

size far

Cretaceous,

had reached

this

legs

to

tiny,

be of any

The

not

from

its

length of

full

late

Tyrannosaurus carried its

like 50 feet,

some

body, from

but

its fore-

longer than a man's, and far too short

couldn't even reach the mouth.

many

on

(which

is

teeth were

skeleton alone that

up it

clumped the Earth.

creature that ever

to six inches long

and

it

was the most nightmarish It is

the largest land car-

record, being at least as massive as the largest elephant

herbivorous) that ever lived.

The enormous it

in

jaws of the Tyrannosaurus could do their work without

clear

nivore

much

They

use.

help, however. Its is

The

was probably something

tail tip,

were

maximum

whose four-foot-long head was

("master-lizard"),

nineteen feet above the ground.

snout to

its

thighs of the Tyrannosaurus

was approaching the practical

The sauropods were

gigantic creatures,

in appearance, of all dinosaurs. structure, with long necks at

show

clearly that

limits for bipedality.

and the most

They were

familiar,

super-elephantine in

one end and long

tails at

the other.

Indeed, they looked like giant snakes that have swallowed giant elephants, with the columnar legs of the latter breaking through

and walking There are

off

with the creature.

clear signs of the bipedal ancestry of the sauropods,

for all that they

clumped down

cases, the forelegs

their backs sloped

The

longest

of

so hard

on four

legs.

remained shorter than the hind

upward and reached a peak all

the

sauropods

is

In most

legs so that

at the hips.

Diplodocus

("double

THE SOLAR SYSTEM AND BACK

202

beam"). Some specimens have been found which measured nearly 90 feet from the snout to the

tip of its

long tapering

No

tail.

other

animal was ever longer except for some of the very largest whales.

However, the diplodocus was a slenderly built creature and

was by no means the most massive dinosaur. The Brontosaurus ("thunder-lizard"), though shorter,

was more massive and may

have weighed up to 35 tons.

More massive

still

was the Brachiosaurus

called because, in the course of evolution,

("arm-lizards,"

so

forelimbs had finally

its

developed to the point where they had overtaken the hind limbs

and were longer). The Brachiosaurus may have weighed up

to 50

tons and was the largest land animal that ever lived. It is

how

hard, though, to be sure

"land animal."

It is

they could clump about on land,

and lakes

as

They found

we can

far

justify the

phrase

very likely that the large sauropods though if

modern hippopotami

necessary, lived chiefly in rivers

do,

and

for the

same

reason.

their food there, as well as a certain protection,

and

the water buoyed up their giant weights.

The

ornithischians,

groups, did not

come

which were the more specialized of the two into their

own

until

about 150,000,000 years

had already

ago, tens of millions of years after the saurischians

developed into a variety of flourishing forms.

The

ornithischians were

all

herbivores and their smaller repre-

sentatives also retained the bipedality of the original dinosaurian

ancestor,

case

though

among

their forelimbs never got as small as

Typical were the duck-billed dinosaurs, broad,

flat

jaw to handle their vegetable

Anatosaurus

was the

the saurischian bipeds.

("duck-lizard"), stood

diet.

which developed a

The

largest of these,

18 feet high.

It

might

re-

semble a Tyrannosaurus when seen quickly, from a distance, but it

was quite harmless unless

Most

it

stepped on you or

fell

on you.

of the ornithischians developed protection against the

THE TERRIBLE LIZARDS

203

One

carnosaurs by developing armor of one sort or another.

known

best

because

its

it

was

first

a roof. Closer study

assumed, protected

armed with two

for

its

tail,

showed

front legs were

more than

little

head contained a brain no

though

it

The

stegosaurus

It

became

is

feet long

tacks

bony

like shingles

double

in a

tail

was

spikes.

of ancestral

bipedality,

half the length of the hind.

larger

than a modern

kitten's,

and more massive than an elephant.

the very epitome of dinosaurian brainlessness. the early Cretaceous, probably before

extinct in

Tyrannosaurus appeared on the scene.

Walt

bony

signs

clear

Its tiny

was 30

back

while the tip of the

pairs of long, pointed

stegosaurus

its

showed that they stood on end

row from neck to the root of the

The

name

its

skeleton was found in association with large

plates which,

on

Stegosaurus ("roof-lizard"). It received

is

of the

The famous sequence

in

Disney's production Fantasia in which a Tyrannosaurus at-

and

kills

a Stegosaurus, though highly effective,

is

very likely

anachronistic.

An

armored ornithischian that evolved

later

than Stegosaurus

and was indeed contemporary with Tyrannosaurus was Ankylo-

and

saurus ("crooked lizard"), ily

armored creature of

all

this

was probably the most heav-

time. It was a low, broad dinosaur that

could not be easily overturned to expose Its

back, from skull to

which, along the

ended

in

sides,

tail,

its

unarmored

was layered with massive bony

were drawn out into strong

a bony knob that probably had the

spikes.

belly.

plates,

The

tail

force of a battering

ram when swung. It was a veritable living tank and I wonder what a battle between it and a Tyrannosaurus would have been like.

Finally there

is

the Triceratops ("three-horned"), which was

built like a super-rhinoceros

and

is

the best-known of a large and

varied family. Its armor was concentrated in

broad

frill

its

head region.

of bone, six feet across, extended from the head

covered the neck.

The

face bore three horns,

A

and

two long sharp

THE SOLAR SYSTEM AND BACK

204

ones over the eyes and a shorter, blunter one on the nose. In addition, the

mouth was equipped with

a strong, parrot-like beak.

For a summary of dinosaur relationships, see Figure

9.

Figure 9 The Dinosaurs REPTILIA

1 ARCHOSAURIA

IT

v

I

lRAPODS

sauropods

TYRANNOSAURUS

iguanodon

v stegosaurus

1

i

ankylosaurus

triceratops

diplodocus,

BRONTOSAURUS. BRACHIOSAURUS

But then came the end

of the Cretaceous, 70,000,000 years ago,

and something happened; we don't know what. All the dinosaurs that then existed, both saurischian and ornithischian, died off in a relatively short time, say a couple of million years. So did the

spectacular non-dinosaur

reptiles,

the ichthyosaurs,

plesiosaurs,

and pterosaurs. So did some spectacular creatures who were not reptiles,

such as the invertebrate ammonites.

There have been almost

as

many

theories to account for this as

there have been paleontologists, and lately there was published a particularly interesting

one which

I

will discuss in the next chapter.

THE DYING LIZARDS

15

Nearly twenty years ago

I

wrote a story called "Day of the Hunt-

ers" in which, in fictional form,

I

new

presented a

theory to ac-

count for the sudden death of the dinosaurs at the end of the Cretaceous period, 70,000,000 years ago.

The I

theory was a simple one.

Toward the end

of the Cretaceous,

suggested, a certain group of small dinosaurs

intelligence, invented missile

had developed

weapons, and hunted

all

the other

dinosaurs to extinction. Then, for lack of any other prey, they

hunted themselves to death,

Why

dinosaurs

with

large

few

fossils.

tures leave

and primates artifacts

But think

I is

.

.

too.

no records of

are there

are

brain

intelligent dinosaurs, then, or say,

capacities?

Well,

not here to defend

defensible.

call

crea-

.

am

I

used

it

my

thesis,

which, actually,

merely to write a

turned out to be what the science-fiction

would

intelligent

Look how few primate fossils we discover, much more recent than the dinosaurs. As for

little

critic,

I

don't

story (which

Damon

Knight,

"minor Asimov") that would develop a not-too-subtle

moral for our own times.

The problem

remains, though.

What

killed off the dinosaurs?

THE SOLAR SYSTEM AND BACK

206

For 150,000,000 species

years,

an astonishing

had dominated Earth's

life

is

them

forms. (I will call

saurs" in this essay even though, as

chapter, this

bulky reptilian

series of

I

"dino-

explained in the preceding

an inadequate term.) All through

this 150,000,000-

year period, from 220,000,000 years ago to 70,000,000 years ago, individual species of dinosaurs

out leaving descendants as

became

far as

sometimes with-

extinct,

we know, and sometimes having

previously branched off other species which, in a sense, replaced

them.

On

other occasions, a species might grow extinct in the

sense that

it

underwent slow changes that turned

species, or into several

About 70,000,000

new

years

however,

ago,

within a couple of million years perhaps) saurian species

A

hundred

became

fifty

extinct, leaving

quite

suddenly

the remaining dino-

all

was easy to explain, because at

years ago this

an age when the Bible was

truth, biologists

had

an Earth, and of

still

among

revered as literal

to square the gathering evidence in favor of

fossil creatures,

both many millions of years

with a Biblical tale that made creation of both Earth and to

(say,

no descendants behind.

that time the doctrine of "catastrophism" was popular biologists. In

new

into a

it

species.

life

old,

seem

have taken place merely 6000 years ago.

A

hint to the solution was found in the tale of the Flood.

Swiss naturalist, Charles Bonnet, suggested in 1770 that

A

fossils

were remnants of extinct species that had been destroyed in

any of a

series of

world-wide cataclysms of which the Biblical

Flood was only the most recent. After each such cataclysm

life

would begin anew, and

say-

ing that

it

Biblical truth could

dealt only with the

be preserved by

most recent of

several different

creations.

The most prominent exponent

of such catastrophism was the

French naturalist Georges Cuvier, who, in the great

skill

he compared the anatomy of the

that they could be arranged in a logical

decades of

first

the nineteenth century, was the foremost student of fossils

fossils.

With

and showed

manner and

fitted into

THE DYING LIZARDS still

existing phyla.

fairly

207

Using hindsight, we can see that what he did

shouted "Evolution!" at the top of

its

voice.

But Cuvier did not accept evolutionary explanations. he carefully pinpointed the location of four places

Instead,

in the fossil

record where there seemed gaps. These, he held, were four examples of Bonnet's catastrophes.

More and more

Alas for Cuvier! their order in all

the gaps disappeared. There

ment the

were discovered and

fossils

fossil

no point

is

in time

record begins (at a point

600,000,000 years ago) to the present, where to exist. Life

In

have existed with

The

dinosaurs.

very

much

little

A ago.

cease

life

still

alive

and

flourishing today that

horseshoe crab

is

an example:

it

has not changed

in 300,000,000 years. in the history of life

when

a great

species have indeed "suddenly" ceased to exist, while a great

other species kept right on going, and this

"partial catastrophe"

killed off

many

variety of habitats— the pterosaurs in the air in the sea, as well as the

other species intact.

mammals

lived right

The

And

plant

hard to explain.

species in a

years

wide

and the ichthyosaurs

clumping land dinosaurs, while leaving early ancestors of the birds

and of the

through the end of the Cretaceous. So did

the ancestors of the reptiles that cestral crocodiles,

is

must have taken place 70,000,000

Something happened that

saurs.

to be

forms of

all

change ever since before the time of the

Yet there have been times

many many

from the mo-

we now know

was created only once.

there are species

fact,

And

time was more and more clearly worked out.

still

live

which were not-too-distant life

lasted

today—even the

an-

relatives of the dino-

through the end-of-the-Cretaceous

dividing line practically untouched.

What a

the answer might be nobody knows, but there have been

number

of interesting speculations

on the matter.

For instance, there might have been a climatic change. The dinosaurs

may have been adapted

to a mild Earth of flat land

208

THE SOLAR SYSTEM AND BACK

and shallow

seas,

with

seasonal variations.

little

The

period of mountain building.

Then came

land heightened and grew

rugged; the sea deepened and grew cold; the seasons

extreme— and the dinosaurs died I

don't like this myself— at

a

became more

off.

least,

not as a sole explanation.

Surely the Earth didn't get climatically unsuitable everywhere.

managed

Creatures have

went bad. The

things

nia; the tuatara

hang on

to

to restricted habitats

when

giant redwoods cling to places in Califor-

clings

to

New

islands off

its

there

must have remained mild and marshy

some

of the smaller dinosaurs might have

Zealand. Surely,

areas

where

hung on,

at least

at least for a

while.

And

could climatic changes alone

relatively

Or furry

the ichthyosaurs in the

kill

unchanging environment of the sea?

perhaps

it

was the

living

environment that did

it.

The

little

proto-mammals, scurrying through the underbrush and do-

ing their best to evade the eyes of the lordly reptilian masters,

might nevertheless have grown for themselves

And

fat

on dinosaurian eggs

left to care

by the dim-witted saurian parents.

eventually the

mammals might have

eaten enough eggs to

block the generations and awoke one morning to find the reptiles gone.

It is

to the

way and

a dramatic story in a

ground since

egg-eaters can

There are

it

presents us

suits us right

down

as heroes (if skulking

be considered heroes).

difficulties,

in existence for a

of course. Primitive

mammals had been

hundred million years by the time the Cretaceous

period drew near

its

increased in numbers

dinosaur eggs.

mammals

it

Or

end.

We

must suppose that they suddenly

and began

else

we can

to take

an unbearable

decide that certain

new

toll

of

species

developed that specialized in these eggs, while leaving reasonably

untouched the eggs of the ancestral

snakes,

And,

and

crocodiles,

lizards,

turtles.

for that matter,

how

did these

mammals

get at the eggs

THE DYING LIZARDS

200.

of the ichthyosaurs, which brought forth their in the sea, in

Then

any

young alive— and

case.

make we sup-

there are the falling-domino modifications that

capital of the fact that life

is

Why should

interdependent.

pose something had happened that affected every single one of the extinct species alike? Perhaps only a relatively small

number

and when these began to dwindle and

of species were affected,

die out, other species which

depended upon the

first

set

for

food or for other necessities also died, and these in turn brought

about the extinction of others—until a whole swatch of the fabric

of

life

was cut out of

This must happen

now.

If

existence.

the time. It can easily be seen as a threat

all

the eucalyptus tree were to

would have to become

become

extinct, too, for

it

extinct, the koala

nothing but

will eat

eucalyptus leaves. If the zebra population were to vanish overnight, the African lions It

would

drastically decrease in

doesn't even have to be a matter of food.

numerous

species

pollination will

Something Cretaceous.

A

plants

of

be wiped out

like that

that

Wipe

numbers.

out bees and

depend on bees

for

cross-

also.

may have happened

at the

end of the

group of species that formed part of a particularly

tight interweaving of life died out,

and with them the

rest of

the

web went. But what could the

initiating factor

have been?

Could a climatic change have killed some species and set the falling? Did a group of egg-eating mammals kill off some species? Was it perhaps the advent of some new strain of

dominoes to

bacteria or virus that killed off certain species in a vast plague?

Was

it,

on the other hand

(as I

have seen suggested), a plant

Did the development of some precursor of modern grasses, which are hard, tough, and ruinous even to the highly adapted molars of the modern horse, bring about the end? The herbivorous dinosaurs, used to softer, more succulent vegetation evolution?

(and possessing teeth to

suit)

began, perhaps, to decline as the

THE SOLAR SYSTEM AND BACK

210

grasslike plants spread species.

And

more and more

at the expense of the earlier

with the herbivores dying, the carnivores that fed

upon them had

to starve as well.

remains only to choose the particular mechanism that set

It

the dominoes to falling, and so far no one has been able are too

many

possibilities to

There

to.

choose from and no reasonable

evi-

dence upon which to base the choice. Indeed, I've

I

haven't even discussed

the possibilities yet. So

all

mentioned only causes that could be one-shots

totally unpredictable. After all,

radical

weather change?

will there

late

sions

will there

will a

be another

really

When

new plague come?

be the equivalent of creatures to eat our eggs or plants

to set our catties' teeth It is

When

when

far,

or, if periodic,

much more

on the

on edge?

interesting, in a grisly sort of way, to specu-

possibility of

reasonably predictable periodic occa-

on which there would be a Great Dying.

We

do, in fact,

find signs in the fossil record of periodic events of this kind, with

the one at the end of the Cretaceous the most spectacular only

because

it

is

one of the most recent and therefore has

record best preserved. There was a of the huge ulating

mammals

still

more

fossil

its

recent Great

Dying

only a couple of million years ago. (By spec-

on such periodic Great Dyings, be it noted, we turn the wheel full cycle and are back to something a little bit

scientific

like Cuvier's catastrophism.

This often happens in science.)

what might possibly give rise to a pemore or less fixed intervals, would place upon life forms and weed them out with a kind

Let's think, then, as to riodic effect which, at

enormous

strain

of blind ruthlessness. It

has sometimes been suggested that there

expectancy to species; that species,

is

a natural

like individuals,

life-

have a lusty

youth, a vigorous prime, a fading old age, and then a senile death.

Perhaps the Great Dyings take place when the species-lifetimes of a large gether.

number

of species just

happen

to reach the

end

to-

THE DYING LIZARDS Actually, there's

no evidence

211

at all that species

the sense that individuals do, but can

we put

grow

senile in

things in other terms?

Instead of talking of senility and life-expectancy,

let's talk

of

mu-

tations.

All species are constantly subject to mutations,

and mutated

individuals arise in each generation. In the vast majority of cases,

and the mutated forms survive

these mutations are for the worse

than do the normal.

less well

and

ever,

if

If there are

species as a whole, the species can it

succumbs to

be weakened to the point where

enemies. In that sense, the species

its

viewed as growing

Then,

too, particular species

creatures have

may

develop a tendency for

grown so

is

more

creature with too elaborate a set of

structure

may

likely to

cer-

happen

specialized that they are oversen-

changes in the environment or in their

sitive to

A

may be

"senile."

tain types of disastrous mutations. This

when

enough mutations, how-

the mutated forms are enough of a burden on the

own

physiology.

armor or too unbalanced a

pass beyond the practical with even a small change.

We ourselves are not immune. We have an extraordinarily complicated

mechanism—in many stages—of blood

clotting.

Our blood mean that

clots

with remarkable efficiency, but the complications

it is

subject to an unusually high failure rate since there are so

many

stages that can

go wrong.

cur in each generation of tion in the clotting live

A sizable number of mutations

oc-

mankind that involve some imperfec-

mechanism. The resultant "bleeders" cannot

long without heroic measures.

Again, the

human

species has developed

an enormous head to

house our giant brains. The female pelvis has barely kept pace

and infants are born with outsize

skulls that

can barely squeeze

through the pelvic opening and even then only at the price of distorting the still-soft cranium. In several ways, then,

piens in

is

at the ragged

mutation

Homo

edge of disaster and cannot afford a

sarise

rate.

Suppose now there

is

an increase

in the

mutation

rate.

If

a

THE SOLAR SYSTEM AND BACK

212

species or group of species

few

tively

likely

is

so well balanced that there are rela-

mutations that can result in death,

that increase moderately well.

it

can endure

on the other hand, a species

If,

is

near disaster in some way, a sudden increase in the mutation rate

might

wipe

just

it

out.

the causes bringing about an increase in mutation rate are

If

temporary, then only certain vulnerable species will go, while the less

may

vulnerable ones

survive, albeit

somewhat ravaged and

changed.

Perhaps

all

the dinosaurs shared something that

made them

particularly vulnerable to the ravages of certain mutations. Per-

haps

went

all

(either directly or as part of the chain of life)

when mutation

rates

climbed at the end of the Cretaceous. Those

that survived (including our vulnerable, that's

And

own

ancestors)

happened

to

be

less

all.

perhaps there are additional periods of increased muta-

tion-rates to

come, and perhaps

we won't

sical chairs,

But what

is it

game

in the

among

always be

What would

that happens?

mu-

of evolutionary

the winners.

raise

the mutation

rate?

One answer

bombarded by hard

why

know,

is

itself,

radiation.

The Earth

There

is

the

one thing. However, there

is

is

ra-

no

that radioactivity should suddenly increase at particuit

can undergo, as

far as

we

that of a slow but steady decrease.

What about the radiation —the

for

In fact, the only change

lar times.

is

radiation of varying origin.

dioactivity of the crust

reason

mind

that springs to

Sun's radiation,

bombards Earth from outer space and the cosmic rays from beyond the solar that

system?

Much it

of this radiation

is

absorbed by the atmosphere before

reaches the Earth's surface and

trically

charged components of

netic field.

As a

much

it) is

of

it

(at least the elec-

deflected by the Earth's

result of this deflection, the

Earth

is

mag-

surrounded

THE DYING LIZARDS by regions

in

which charged

21$

high density, dance back

particles, in

and forth along the magnetic lines of force (the

and leak down to

Van

Allen belts)

into the upper atmosphere in the polar regions

form the auroras. Clearly,

if

Earth's magnetic field were to vanish, charged par-

would no longer be

(including the cosmic-ray particles)

ticles

deflected

and more of them would

would be

effect

mutation

strike

the Earth's surface.

The

to raise the radiation level and, therefore, the

rate.

But could the Earth's magnetic Possibly!

vanish?

field

Consider the Sun, for instance.

sunspot cycle, as

we

all

know. That

the

is,

It

has an 11-year

number

of sunspots

rises steadily, reaching a maximum, then falls to a minimum that is nearly zero, then rises to another maximum, and so on. The

length of time from

maximum

maximum

to

averages 11 years,

though the actual time lapse between recorded maxima has varied

from 7 to 17

The

years.

sunspots have magnetic fields associated with

the orientation of the magnetic ispheres. If in the

them and

opposite in the two hem-

field is

Northern Hemisphere, spots have the north

magnetic pole on top (so to speak), those in the Southern Hemisphere have the south magnetic pole on top. Then, in the next cycle,

the situation switches.

The Northern Hemisphere

spots

have the south magnetic pole on top and the Southern Hemisphere spots have the north magnetic pole there. cycle magnetically as well as numerically It is

not certain whether

this

To

restore the sunspot

one must wait 22

years.

means that the Sun's general mag-

netic field regularly reverses polarity so that every 22 years the

Sun's north magnetic pole becomes

its

south magnetic pole and

vice versa. If this happens,

one must not suppose that the mag-

netic axis suddenly topples

and turns

pens

is

that the entire magnetic field

and then begins to strengthen again

over.

What

probably hap-

weakens and declines

to zero

in the opposite direction, with

THE SOLAR SYSTEM AND BACK

214

sunspot minima probably coming at times of zero

happens (assuming

Can field?

it

field.

Why

this

does happen) no one knows.

much

the same thing happen to Earth's

Well, there are indications in the rocks

when

the north magnetic pole

now

(as, for instance, in

that there have been

the orientation of magnetized minerals) periods in Earth's history

smaller magnetic

the south magnetic pole was where is

and

vice versa. Presumably, this

happens because the Earth's magnetic

gradually fades to

field

zero, then strengthens in the opposite direction.

As

a matter of fact,

seems that the Earth's magnetic

it

indeed been weakening during the centuries

The American

observation.

Robert Gunst point out

it

has

McDonald and its

strength since

by

will reach zero

it

Between 3500 and 4500, the magnetic

a.d.

field

has been under

Keith

geophysicists

has lost 15 per cent of

1670 and at the present rate of decrease

4000

it

field will

not be

strong enough to ward off any charged radiation to speak of.

We

ourselves won't live to see

two thousand let

of course, but a matter of

it,

human

years isn't long even in terms of

alone in terms of geologic eras, and

it is

civilization,

not something

we can

dismiss with a shrug.

And

it is

a shame, for

close to a reversal.

may have

the rocks,

What 3500,

we

The

will

will

artificially,

it

seems rather bad luck for us to be so

last reversal, as nearly as

taken place as

much

happen when the magnetic

we can

tell

from

as 700,000 years ago. field fades?

Perhaps, by

have the technological capacity to shield the Earth

but suppose we don't. Will the mutation rate go up in

the thousand years of non-shielding and "senile" species?

Will we be among the

kill

the

senile? Is

less

stable or

Judgment Day

coming? Perhaps not. After field

may have

all,

reversed

when

the magnetic

there was no Great

Dying among

700,000 years ago,

itself,

man's hominid ancestors. They

mutation rate had gone up. At

may even have improved least

if

the

man's brain grew in volume

with explosive speed (in terms of ordinary evolutionary rates of

THE DYING LIZARDS change) and one might speculate that

215

was the

it

result of

an

unusual number of lucky mutations. Besides,

have seen calculations which showed that even

I

there were no magnetic field at

all

the surface of the Earth would

particles, the level of radiation at

not

increase the mutation rate dangerously.

rise sufficiently to

Suppose we tackle

if

and no interception of charged

it

from the other end. Forget Earth's mag-

netic field for a while,

and ask whether the radiation bombard-

ment might

increase drastically at the source.

X

its

rays

from

companies a giant tity of this

The Sun

sends out

corona as a matter of course and occasionally ac-

with a burst of soft cosmic

flare

radiation

too small to

is

harm

rays.

life,

The quan-

but what

if

it

suddenly increased in intensity considerably. It's

not

likely.

The Sun could

becoming much more

necessary to

ray emitter without of ultraviolet

and

scarcely

undergo the changes

active as

an X-ray and cosmic-

becoming much more

visible light as well,

active in the emission

and the Sun doesn't do such

things.

From

we know) about the Sun and about stars generally, and from everything we can deduce from the fossil record, an erratic Sun is not in the cards. Our good everything

we know

old solar heating plant ticeably

What we

utterly reliable

is

and hasn't changed no-

from eon to eon. about cosmic rays from sources other than the Sun?

These are the only that

(or think

significant nonsolar samples of

hard radiation

get.

Lately, K.

D. Terry of the University of Kansas and

Tucker of Rice University have speculated on the possible

W.

H.

effects

of stars going supernova in the neighborhood of our solar system.

They point out

that a good massive type II supernova (involv-

ing the virtually total explosion of a star ten times the mass of our

Sun) would give

off

up

to 2

of cosmic rays alone, emitting at most.

X

10 51 ergs of energy in the form

it all

over the period of a few days

THE SOLAR SYSTEM AND BACK

2l6

Let us say that of a week. It

this cosmic-ray

energy

would then be equivalent

the total energy delivered by the

How much were 16

Sun

times

1 trillion

in that week.

cosmic ray energies reaching us from

still

be equal to the Sun's

tion for that week. Undoubtedly, that

However, there are very few

enough to give

rise to

would

stars of

are as close to us as 16 light-years,

make

total radia-

fry us all properly.

any kind

now,

that, right

and of those that are none are

The

the biggest kind of supernova.

only close star that could go supernova at that would

delivered in the space

of that energy would reach us? If such a supernova

light-years away, the

that vast distance would

large

is

to roughly

all

would be

Sirius

and

a rather mild one.

However, we don't have to

insist

on a

total frying.

Consider

supernova explosions that take place at great distances and bathe us with smaller concentrations of cosmic rays. Those smaller concentrations might

room

ume

for

many more

of space goes

be enough to cause trouble and there

still

supernovas far away than close by.

up

as the

number within

vol-

cube of the distance and the number

of supernovas within 200 light-years as the

The

is

is

two thousand times

as

many

16 light-years.

Terry and Tucker point out that the present dose of cosmic rays reaching the top of the

per year, which

is

very

atmosphere

little,

really.

is

And

equal to 0.03 roentgen yet,

judging from the

frequency of supernova, their random positions and

sizes,

they

cal-

culate that Earth could receive a concentrated dose of 200 roentgens, thanks to supernova explosions, every 10,000,000 years or so,

on the

average,

and considerably

larger doses at correspondingly

longer intervals. In the 600,000,000 years since the

began there gen

is

flash (!)

fossil

record

a reasonable chance that at least one 25,000 roent-

reached

us.

Perhaps then the periodic Great Dyings in the history of reveal the explosions of large stars within a

few hundred

life

light-

years of our solar system.

And

perhaps the effect

is

worst

when such

a sizable explosion

THE DYING LIZARDS just

217

happens to come when the Earth's magnetic

field is in

period of reversal and the unshielded surface gets the of the cosmic-ray frying pan. After

now, much weaker than at times

make

its

our magnetic

all,

maximum. There

its

benefit

full

weak

field is

are probably

when even moderately strong doses of cosmic rays might not it, but now they will, and by 3 500 they will do so even more

A

readily.

supernova that in 300,000

would not have

b.c.

affected

Earth, might lay us pretty low now.

Well, then,

if

we

can find a record in the rocks that about

70,000,000 years ago there was a magnetic field reversal, and

if

we

can find a record in the skies that 70,000,000 years ago there was a

and

spectacular supernova in our neighborhood,

some way strongly

if

of showing they were simultaneous, then

tempted to look no further

there were I

would be

for the cause of the

death of

the dinosaurs.

And what about

our not-too-distant descendants? Must

our breaths and cross our fingers for them?

What

if

we hold

during the

thousand-year interval of virtually no shielding whatever, Sirius goes supernova, or a larger, but

The chances

more

are extremely small.

within several hundred light-years tionary development to then,

we

don't

know

all

make there

is

distant, star does it?

As

far as

we know, no

star

sufficiently late in its evolu-

a supernova explosion likely—but, is

to

know about what makes

a su-

pernova explode, and when. It just

barely could be.

enough to make

a Dying,

ensure the immunity of

And

if

we

be a kind of

die

The

cosmic-ray incidence

Great or

Homo

Little,

sapiens

and the crocodiles and

reptilian last laugh at

if

and there that

is

comes

may

go up

nothing to to pass.

lizards survive, there

our expense.

may

COUNTING CHROMOSOMES

l6

am

Alas, I

a square.

secret urgings

nical

I

don't use mind-expanding drugs,

toward psychedelism,

term for marijuana); in

smoke tobacco.

I

wear

my

I

fact,

hair

I

I

have no

smoke pot (the

don't

tech-

don't even use alcohol or

and sideburns moderately

short,

have neither beard nor mustache, dress cleanly and conservatively (if,

on

occasion, sloppily),

and speak

a reasonably precise

English. I

do

all this as

a matter of personal choice, however,

out deep, moral convictions.

I

have no objections whatever to the

eccentricities of others, provided they leave

vided those eccentricities do no I

and with-

harm

to

me

to mine,

anyone but

and pro-

their owners.

consequently spring to the defense of the long-hairs against

my fellow

squares. In

ing out that those

makes them look

time,

I

have published

object to long hair

like girls"

shaving, for the very stance.)

my

who

same

pointit

ought to object to the practice of

reason. (See the next chapter, for in-

Yet they don't; but usually object

makes nonsense of the

little essays

on boys "because

logic with

to beards, too,

which they

which

try to invest their

prejudices.

In fact,

it

seems to

me

that the whole business of telling the

COUNTING CHROMOSOMES sexes apart at a glance

is

overrated.

Why

219

does one have

to quote

one

to, if

doesn't have a personal interest in a particular individual?

like

I

Roland Young's "The Flea":

And

here's the

happy bounding flea—

You cannot tell the he from she. The sexes look alike, you see; But she can So

and

was with some chagrin that

it

from a fall

tell f

girl

so can he.

I

discovered that telling a boy

can be important indeed and not at

of 1967, a Polish

woman

Her unclothed body was

clearly female,

placed that femininity in question.

all

simple. In the

was inspected by doctors.

athlete

but more subtle

The chromosome

tests

count,

it

seems, was wrong.

And what

are these

chromosomes that can thus contradict the

evidence of one's eyes in so vital a matter and get away with

Aha,

as

you have

just guessed,

The chromosomes body's

cells, visible

five to ten

I'm about to

tell

it?

you at length.

are tiny, flexible, rodlike objects within the

only under the microscope.

It

would take some

thousand of them, strung end to end, to stretch across

a single inch.

Even with cell.

Like the

through them cells

a microscope, they are hard to see in

the

easily.

For a century and a

cell,

half, microscopists studied

without seeing the chromosomes.

But then, a century ago,

some

the living

they are translucent and light passes

rest of

of the

new dyes

began treating

biologists

with

cells

that chemists were then starting to syn-

thesize. Different parts of a cell contain different chemicals;

parts therefore absorb a particular dye

and some do

under such treatment, begins to display

its

not.

some

The

cell,

inner structure in tech-

nicolor splendor.

In 1880, a

German

biologist,

Walther Flemming, was using a

THE SOLAR SYSTEM AND BACK

220

red dye, which clung only to certain patches inside the cell nucleus.

(The

cell

nucleus

in the cell. It

one

a small body,

is

more or

located

less centrally

was early found to control the manner

which

in

two cells— the key process of growth and

cell divides into

development.) Flemming called these colored patches of nuclear material "chromatin," from a Greek

Flemming was

word meaning

thing to do with the nuclear control of tunately, chromatin could only

the dye killed the

What

he

tissue, in

cells

were in

and then running

material collected

cell

into

itself

stills,

putting

moving picture

off a

turned out that as a

what looked

name of "chromosomes" ("colored moment of division, the chromosomes other.

The

"daughter

mass of

At the

separate into cell

and the

were produced, each containing

cells"

new

like a tangled

crucial

two equal rest to

then divided through the middle, and two

cell

Once

of chromosomes. in each

film.)

bodies").

one end of the

to

like taking

in the right

These pieces were soon given

the

one half going

was

them

got ready to divide, the chromatin

short pieces of cooked spaghetti.

parts,

cell

He

at every stage of

details of the process. (It

a set of scrambled photographic

It

stages of division.

putting the different stages in the right order,

he could work out the order,

growing

slices of rapidly all

and caught the chromatin

slice

By

be seen when colored by dye, and

was to study thin

did, then,

that process.

Unfor-

division.

cell

cells.

which individual

dyed the entire

"color."

eager to learn whether the chromatin had some-

division

its

own

the

new

supply

was complete, the chromosomes

broke up into patches of chromatin again.

Further study showed that a particular species of creature contained the same

number

of

chromosomes

one important exceptional case which not always easy to

tell

tangle together, and say

where one

what

when

leaves off

this

I'll

number

there are

in each of its cells (with

get to in a while)

is,

many

since the

of them,

.

It is

chromosomes it is

hard to

and another begins. The best attempts

COUNTING CHROMOSOMES at counting

chromosomes

in

human

cells

chromosomes per

that there were 48

more painstaking count showed only

Chromosome counting

seemed

to show, at

first,

In 1956, however, a

cell.

46.

now become

has

221

rather simple. Cells

are treated with a chemical that forces the process of cell division to stop short at just the point clearly shaped.

with a weak to swell,

These

salt solution

become

with very

cells,

little

puffy,

trouble,

where the chromosomes are most

caught in mid-division, are then treated

that causes the individual

and move and

in

They can then be counted

apart.

human

chromosomes

46 chromosomes turns

cells,

out to be correct.

But

this raises a question.

chromosomes?

when

a cell divides, shouldn't each

mosomes? And chromosomes be No! the

How

still

human

cells

have 46

new

cell

have merely 23 chro-

moment,

number

that momentarily doubled supply

of

there are 92

new

dividing cell and, after division, each

cell

number

of

fewer?

doubles. For a

pens at each

all

at the next division, shouldn't the

Just before cell division, the

cell

can

the chromosomes divide into two equal parts

If

and

division so that

is

chromosomes within chromosomes

cell

in the

has exactly half of

back to 46 again. This hap-

(again with one exception)

chromosome number remains 46 no matter how many times cells divide and share out their chromosome content.

the

The involvement

chromosomes in cell division is, as a matter of fact, very precise. The chromosomes aren't put together higgledy-piggledy at all. Chromatin comes together to form chromosomes of specific size and shape, and they are always formed of

The human

contain 23 pairs of chromosomes; these have been carefully numbered in order of decreasing length, from in pairs.

1

cells

to 22, with the twenty-third pair being a special case.

At the midpoint of the process of cell division, each chromosomes brings about the formation of another pair like itself. Since it

forms a replica of

itself,

the process

pair of

is

exactly called

THE SOLAR SYSTEM AND BACK

222

"replication." After replication,

and when the

are present; in such a

way

that

two complete

cell divides,

a particular pair

if

Each new

sets of

moves

one direction

in

its

ends with a complete

replica

moves

set of

chromosomes, one pair of each of the

in the other.

chromosomes

the chromosomes separate

cell

no

23, with

pair

missing and no pair added.

This careful division is

made up

necessary.

is

Each chromosome, you

of strings of genes, thousands of

mosome. Each gene

them

see,

in each chro-

controls the formation of a particular

enzyme

molecule, which in turn controls a particular chemical reaction going

on

in the cell.

The chromosomes, the

They

cell.

carry

does or can do

is

then,

it is

exact set of

instructions, so to speak. Everything the cell

made

enzyme supply and rally,

therefore, are the "chemical supervisors" of

its

possible

by the particular nature of

this is dictated

by

its

important that every new

chromosome

pairs so that

tions for the performance of

cell in

may

it

the body get an

possess the instruc-

its tasks.

(These instructions are basically the same for they are

somehow modified

so that liver cells are

part, brain cells in another, skin cells in

still

each with widely different functions and in

its

chromosomes. Natu-

all

cells,

produced

in

on-

another and so

abilities.

which the chromosome instructions are modified

but

one

The manner is still

a bio-

chemical mystery, however.)

The cision,

process of replication passes

from

cell to cell

on from parents appropriate

from set of is

to offspring?

chromosome

How

is

a

how

pre-

are they passed

new body

started with

instructions?

done by way of the sex cells. The female produces egg the male produces sperm cells. Each of these is distinguished

This cells;

chromosomes on, with

within a body. But

is

all

other

cells

by the

fact that they contain only half a

chromosomes; only one chromosome of each

the aforementioned exception to the rule that

contain the same

number

of chromosomes.)

all

pair.

human

At some

(This cells

stage in

COUNTING CHROMOSOMES the formation of the sex

cells a

without prior replication.

The

chromosome

egg

cell is

rest to

cell.

the other. tiny,

That, however, need not be wounding

to the male's ever-sensitive ego.

The

egg

cell is large

contains a sizable food supply in addition to contains chromosomes only.

cell

one of

tremendously larger than the insignificantly

tadpole-shaped sperm

sperm

division takes place

23 pairs simply separate,

each pair going to one side and the

The

223

its

because

it

chromosomes. The

From

the instructional

standpoint, the two varieties of sex cells are equal.

The

sex cells

produced by a particular individual are not

may be

all

alike.

Every chromosome pair

pair,

but the two individual chromosomes of the pair are not

exactly alike. (In other words

not

"Aa" may be

The two chromosomes

like "a.")

far as size

like every other

chromosome

"Aa," but "A"

like

may be

of a pair

is

twins as

and shape are concerned, but the molecular structure

may be significantly different. One particular sex cell may get chromosome "A" of the first pair or it may get chromosome "a." It may get chromosome "B" of the second pair or chromosome "b" and so on. The number of different combinations that may be formed by taking, at random, of the genes they contain

one of each of 23 twenty-three is

2*s

different pairs can

and multiplying them

be found by starting with together, 2 23 .

The answer

8,388,608.

Even

chromosomes can sometimes wrap themselves about each other and swap pieces in any of a thousand different ways. A sex cell may get a chromosome that

is

this

is

conservative, for pairs of

mostly "A" but slightly "a."

Then,

too,

it is

possible that a particular gene within a chro-

mosome may undergo

a change even while

it

is

part of a living

cell.

There are so many chances of variation tern received sex cell

of

by each sex

cell

that

it is

in the

instructions.

pat-

quite possible that each

produced by a single individual has a

chromosome

chromosome

slightly different set

THE SOLAR SYSTEM AND BACK

224

A

new

individual

is

formed only when a sperm

male parent combines with an egg produce a cells,

—23

"fertilized

the fertilized pairs,

ovum now its

possibilities of

from the

cell

of the female parent to

such a union of sex

result of

has a complete set of chromosomes

with one of each pair from

of each pair from

The

ovum." As a

cell

its

mother and the other

father.

combination of sperm

cell

and egg

cell pro-

duces a random reshuffling and recombination of genes from

two separate individuals to produce a new creature with a brand new set of chromosome instructions, not like that of either parent. With all the possibilities for variation among the sex cells produced by each parent,

mated 60

seems quite certain that each one of the

it

billion

humans who have

distinctly different

lived since time

from every other one, and that

tinue for the indefinite future. (Identical twins,

some

reason, divided into

this will con-

triplets, etc., are

exceptions for they arise from a single fertilized for

esti-

began was

ovum

two or more separate

that has, cells

that

then develop independently.)

This ceaseless variation in instructions from generation to generation through sorting

and recombination of chromosomes

is,

in fact, the probable biological basis for the value of sex. Creatures

can, after

all,

reproduce without

offspring without help; ever,

some

two parents combine

to

sex,

with one parent producing

types of species do this.

of chromosomes that takes place introduces scale

not possible otherwise.

species

to

is

greatly increased

When, how-

form a new individual, the

The

and

it

variations

and

versatility of a

flexibility

can evolve

much more

meet changing conditions. Sex has therefore

glad to say) replaced nonsex altogether

shuffling

new

among

all

(I

am

on a

quickly

personally

but the simplest

creatures.

The moment is

of fertilization—of the union of sperm with

significant with respect to the twenty-third pair of

It is

egg-

chromosomes.

the only one that need not be a true pair in outward ap-

COUNTING CHROMOSOMES pearance. In the female of

two

fairly

225

however, the pair being composed

it is,

long chromosomes, called "X-chromosomes."

male, having two of these, can be designated as an In the male, the twenty-third pair

them

normal X-chromosome, but the other

a

is

not a true

is

only about a quarter the length of the X.

chromosome" and the male

therefore

is

sex difference, the twenty-third pair of called the "sex

is

A

pair.

One

XY

and an in a

of

a stunted one,

The short one is a an XY. Because of

"Ythe

chromosomes are often

chromosomes."

Apparently, the differences in the enzymes produced by an set a

one ending

fe-

XX.

body on one or the other of two

in a female

XX

different paths,

anatomy and physiology and the other

male version.

The Y-chromosome means

in the male is largely nonfunctional, which X-chromosome has no spare as backup and a bit more vulnerable to certain genetic ab-

that the male

males are therefore

A

normalities.

defective gene in an

shows up; in a female

it

may be

X-chromosome

in

a

male

countered by a whole gene in the

other X-chromosome.

Some

"sex-linked characteristics," such as color-blindness

and

hemophilia, which appear in males but rarely in females, are very noticeable. Others are not but

female

may account

for the fact that the

span proves to be up to seven years longer than that

life

of the male once the dangers of childbirth are banished by

mod-

ern medicine.

When egg

a female forms egg

cell gets

content

is

When sperm

concerned,

a

cells

two broad

one X. As

all

egg

male forms sperm

end up with an varieties of

the

cells,

far as the overall

pair divides

and each

shape of the chromosome

cells are therefore alike. cells,

X and

sperm

XX

cells

the

XY

pair divides. Half the

half with a Y.

There

are, thus,

formed.

In the activity that precedes fertilization, several hundred million

sperm

cell.

The sperm

cells are released in

cells

the neighborhood of a single egg

(about half of them

X

and

half

Y)

race

THE SOLAR SYSTEM AND BACK

226 for the egg

cell,

reach the egg

XX

with winner take

first

and

fertilizes

and develops into a female. an XY; that

the result

is

and so

happens that boys and

it

is,

all. If

it,

an X-sperm happens to

then the

a male.

fertilized

ovum

an

is

Y-sperm makes the grade,

If a

The

chances are about equal

are born in roughly equal

girls

numbers.

we are assuming that all will go well, and not be so. The process of cell division, involving the So

far

cation of the immensely complex division

between two new

cells,

chromosomes plus can

easily

yet this

may

careful replitheir precise

go wrong and some-

times does. Errors can take place. Sometimes these will only involve individual genes

somewhere along the

chromo-

line of the various

somes. Such "mutations" can be fatal or merely disadvantageous.

There are even occasions when a mutation can be

favorable. affected,

but

an entire chromosome that goes wrong? In the process of

cell

But what division,

not a submicroscopic gene that

if it is

is

with the chromosomes being yanked roughly apart,

may happen

that one of

them may break

in

two and come back

together again with one piece rear-side forward.

chromosome-piece has speak,

and

is

its

it

A

backward

instructions reading differently, so to

not normal.

Or what if a chromosome breaks in two and does not reunite? The pieces might travel to opposite ends of the cell. One daughter cell may get a chromosome pair plus an extra piece of a third chromosome, while the other daughter

cell gets

not quite

all

of a

pair.

Such chromosome aberrations are much more changes in individual genes.

hundreds of genes

all

ring of instructions

is

at once.

serious than are

Chromosome breakage can

involve

Such a wholesale blurring and

almost certain to produce

cells

slur-

that cannot

and go through the intricate process of growth and division. If such chromosome breakage takes place in the cells of a hu-

live

COUNTING CHROMOSOMES man

adult,

cells,

do not count

One cell, or even a hundred much among trillions. The damaged cells

need not be

it

for

227

serious.

drop out and are replaced by those produced through correct vision. In

the

fact, since

true-formed

show up,

cells

accurate than

And what

it

damaged

may

to

be

more

far

really be.

the error takes place in the production of sex

if

and one appears with such such a sex

division seems

cell

cell

di-

drop out and only the

cells

a

chromosome

cannot develop

far.

cells

aberration? In general,

Those children who do man-

age to be born usually lack serious chromosome aberrations and

we get the idea that the processes of egg and sperm formation are much more foolproof than they really are. Heaven knows how many botched jobs are scrapped and never come to view.

A

hint of the botching arises from the fact that a few aberra-

tions

manage

some

five

to

make

it

and babyhood. One birth out of

to birth

hundred, for instance,

is

drome," or "Mongolism." (The

which seem to East Asians.)

The

of an infant with

latter

name

refers

"Down's

syn-

to the eyes,

slant in such babies in a fashion associated with

The

condition involves serious mental retardation.

cause of the syndrome was not

three Frenchmen,

Lejeune,

J.

the chromosomes in

cells

M.

known

until 1959,

when

Gautier, and P. Turpin, counted

from three cases and found that each

one had 47 chromosomes instead of 46. It turned out that the was in the possession of three chromosome-2i's, a normal

error

pair plus to a

an additional

chromosome

single.

formed

The sex 21, as cell

it

cell

first

disease ever pinned

aberration.

Apparently, what happens cell is

This was the

after

is

that every once in a while, a sex

an imperfect division of chromosome-pair

21.

that finally appears, instead of having one chromosome-

should, has two or

none

at

all.

After union with another

with the normal single chromosome present, the

ovum has either three, 21-21-21, or one, 21. The case of the three is Down's syndrome. The until recently, never

been detected.

It

fertilized

case of one had,

was suspected that the

THE SOLAR SYSTEM AND BACK

228

possession of one presented so serious a disadvantage for the de-

veloping egg that

it

never reached term. But then, at the Bethesda

Naval Medical Center half-year-old girl

was the

first

1967, a mentally-retarded three-and-a-

in

was found to have a

chromosome-21. She

single

human

discovered case of a living

being with a miss-

ing chromosome.

Cases involving other chromosomes seem

common

less

but are

turning up. Patients with a particular type of leukemia show a tiny

chromosome fragment

extra

in

their

"Philadelphia chromosome" because city.

Broken chromosomes,

normal frequency

cells.

it

was

in general, turn

This

is

called

the

located in that

first

up with

greater than

in the cells of people with certain other (not

common) diseases. The sex chromosomes,

very

too,

can be involved in aberrations.

can be formed with two X-chromosomes or none.

A

An

sperm

egg

cell

cell

can be formed with both an X- and Y-chromosome, or with

neither. In such cases, a fertilized

XXY,

or

Such rarely

XYY,

or simply

cases are not

X

ovum may be formed

that

is

or simply Y.

common, perhaps because such embryos

complete their development. Nevertheless, they have been

detected.

A person

born with an

XXY

set in his cells

has the out-

ward appearance of an underdeveloped male. On the other hand, X and XYY individuals seem to have the outward underdeveloped characteristics of a female.

The

individual

who made the headlines in Ewa Koblukowska,

such an abnormality was twenty-one-year-old Polish a

girl,

girl.

connection with tall,

muscular

She always thought of

herself as

a

and, although flat-chested, had the sexual organs of a

girl.

She was, however, an excellent athlete and the question arose as to whether she might not have some male characteristics, including larger

and stronger muscles than females have

generally. This

would be no crime, of course, but it would then be unsportsmanlike to have her compete with normal females. Her chromosomes were counted and the six doctors (three Rus-

COUNTING CHROMOSOMES sians

and three Hungarians) found themselves

announcement Naturally,

it

229

in agreement.

chromosome too many."

would be useful

methods that would cut

down on such chromosome

to devise

aberrations. Failing that,

it

certainly be advisable to avoid conditions that increase

some

The

was that there was "one

aberrations. Biologists are well acquainted with a

would

chromo-

number and

of these. Energetic radiation, for instance, will do so,

will

produce gene mutations, too. It is partly for this

reason that world public opinion bore

so heavily against nuclear

The

bomb

the open atmosphere.

tests in

radioactive particles produced

down

might not

outright, but

kill

they would slightly raise the mutation rate and increase the an-

nual production of defectives of one sort or another.

But

it

is

not radiation only that encourages mutation. There

do so— chemicals that

are certain chemicals that

chromosome likely to

replication

come

and separation.

in contact with

Human

most of the

interfere with

beings are not

particular chemicals

that chemists work with, but a few years ago there was the case of the tranquilizer thalidomide, which produced deformed babies

once

it

was given to pregnant women.

chromosome Anything ple

It

undoubtedly produced

aberrations. else?

Might

there be such a substance to which peo-

had not been exposed

till

recently,

but which was

now com-

ing into wider use?

This thought occurred to Dr. University of

New

York

Maimon M. Cohen

of the State

in Buffalo. In June, 1966, after visiting a

hippie hangout out of curiosity, he found himself wondering about

the bizarre behavior of some of them.

Were

their cellular instruc-

tions being interfered with?

His work dealt with chromosome counts so he could check. Back at his laboratory,

he began work with white blood

cells,

which

could be obtained easily and in quantity from any drop of blood.

He exposed some of them to a weak solution of LSD, then studied their chromosomes. He found they showed twice as many broken

THE SOLAR SYSTEM AND BACK

23O

and abnormal chromosomes had not been exposed

What test

to

LSD.

about exposure to

white

cells

did which

as ordinary white cells

LSD

He

body?

inside the

began to

from people who admitted having used LSD. So

did other experimenters, after the

reports

first

began

to reach the

world of science.

There seemed rather general agreement. The white

cells

of

LSD-users had unusually high numbers of broken and abnormal

chromosomes.

Was

it

only in the white

particular, did

chromosome

or was

cells,

it

in cells generally? In

aberrations take place in the sex-cells

of LSD-users to a greater extent than in non-users? If so, there

would be more defective

births

among LSD-users than among

others.

among what

wait for births

It is difficult to

still

is

segment of the population, so experimenters turned mals. Small

and, in a

amounts of

number

LSD

a small to

ani-

were injected into pregnant mice

of cases, there were serious abnormalities

and

malformations in the mouse embryos.

LSD

makes

the brain

its visible

influence felt on the nervous system and

the sake of the pleasure obtained from the

(it is for

mental aberrations and hallucinations so

it is

not surprising that

its

effect

on the seventh day of pregnancy.

it

produces that

on mice

It

is

it is

used),

most pronounced

then that the brain and

is

nervous system are being rapidly formed; and

it

brain mal-

is

formations that most frequently appear in the affected embryos.

The equivalent period —which generally comes

human pregnancies is the third week before a woman knows she is pregnant

in

and can therefore stop using the drug, This adds a new dimension to

own is

feelings against

an agent of harm

it

—since

if

she

use,

is

a user.

and strengthens

it

my

not merely an eccentricity, but

to individuals other than the user.

from the psychotic episodes cide)

it is

LSD

Quite apart

produces (up to murder and/or

and from the danger of producing a permanent

sui-

psychosis,

COUNTING CHROMOSOMES it

of

231

may increase the rate of defective births and multiply the load human tragedy upon our planet. The case is not yet proven, of course, but the indications are

that LSD-users are undergoing the equivalent of a private bath of radiation fallout.

fun

If so,

selves

may be fun—but

and higher

for their

the price can

come high

for

them-

unborn children.

Note: Since the above chapter was written (in January, 1968), chromosome anomalies has skyrocketed. It turns out

interest in

that individuals with an

handle.

They

are

tall,

XYY

combination are

difficult

people to

strong and bright and are characterized by a

who killed eight be an XYY. A murderer

tendency to rage and violence. Richard Speck, nurses in Chicago in 1966,

was acquitted

XYY

is

supposed to

in Australia in October, 1968, because

and therefore

he was an

4 per cent of the male inmates in a certain Scottish prison have turned out to be XYY. irresponsible. Nearly

There are some estimates that

many I

as

1

think

XYY

combinations

may

occur in as

man

in every 3000.

it

only reasonable to begin thinking of a routine

chromosome

is

analysis of everyone

and of every newborn

child.

UNCERTAIN, COY, AND HARD TO PLEASE

17

What

with one thing and another,

of reading of Shakespeare lately*

I

have been doing a good deal

and

I've noticed a great

many

things, including the following: Shakespeare's romantic heroines

are usually

much

and moral

strength.

Juliet

takes

superior to his heroes in intelligence, character,

strenuous

and dangerous action where Romeo (Romeo and

merely throws himself on the ground and weeps Juliet); Portia plays a difficult

and

active role

where Bassanio can

only stand on the sidelines and wring his hands (Merchant of

Venice); Benedick for Beatrice

is

a quick-witted fellow but

(Much Ado About Nothing). Nor

he is

isn't a

match

Biron a match

Orlando a match for Rosasome cases, it isn't even close. Julia is infinitely superior in every way to Proteus (Two Gentlemen of Verona) and Helena to Bertram (Ms Well That Ends Well). for Rosaline (Love's Labour's Lost) or

lind (As

The

You Like

It). In

only play in which Shakespeare seems to

chauvinism

is

The Taming

of the

Shrew and

fall

prey to male

a good case can

be

made out for something more subtle than merely a strong man beating down a strong woman— but I won't bother you about that here. *

Because I'm writing a book on the subject,

that's

why.

UNCERTAIN, COY, AND HARD TO PLEASE Yet, despite

never hear of anyone objecting to Shake-

all this, I

on the ground that he presents women

speare

never heard anyone say, "Shakespeare

On

understand women."

233

is

the contrary,

I

inaccurately.

right

all

I

have

but he doesn't

hear nothing but praise

for his heroines.

How

is

then, that Shakespeare—who, by

it,

human

has caught the

race at

its

truest

common

consent,

and most naked under

women

the probing and impersonal light of his genius— tells us anything, the superior of

are, if

so

many

ferior to

by and

large,

me

me.

It

accept their

(to put

it

me

concerns

own

inferiority.

is

my

and

I

want

and

these, I hope, will

To

to explain

be more rational

reasons for this belief.

in this

I

would

admit there are certain ineradicable physio-

let's

between

la difference!" leaves

are there

Are there

men

men and women.

(First

one to

yell

the room.)

any differences that are primarily nonphysiologi-

intellectual,

temperamental, emotional differences

and that

that you are sure of

hold for

my

in the present.

logical differences

But

is.

Woman in the future, in the light of what Woman in the past and what is happening to

begin with,

"Vive

be

human

about

has happened to

Woman

con-

as a science-fiction writer, especially, because

belief that future societies will

like to speculate

from

it

most simply) because everything concerns

rational in their treatment of 51 per cent of the

respect,

cal?

are in-

women,

matter concerns me. Well,

this

race than our present society It

women

say "us" without qualification because

I

science fiction involves future societies,

more

and yet

in all that counts,

of us nevertheless remain certain that

men.

You may wonder why cerns

men

in a broad, general

all cultures, as

will serve to distinguish

way?

I

mean

women

differences that will

the physiological differences do, and

dif-

ferences that are not the result of early training.

For instance, fined" bit, since

I

am

we

not impressed by the

all

know

"Women

are

more

re-

that mothers begin very early in the

THE SOLAR SYSTEM AND BACK

234

game

hands and

to slap little

say,

"No, no, no, nice

little girls

don't do that." myself, take the rigid position that

I,

and that the only

cultural influences

we can

never be sure about

safe distinctions

between the sexes are the physiological ones. Of

we can make

these, I recognize

two:

Most men

1.

are physically larger

and physically stronger than

most women.

Women

2.

get pregnant, bear babies,

and suckle them.

Men

don't.

What

can

seems to

me

we deduce from that this

vantage with respect to

enough

is

men

two

these

to put

differences alone?

women

in a primitive

It

at a clear disad-

hunting

society,

which

there was prior to, say, 10,000 B.C.

is all

Women,

after

would be not quite as capable at the rougher and would be further handicapped by a cer-

all,

aspects of hunting

pregnancy and certain distractions while

tain ungainliness during

taking care of infants. In a catch-as-catch-can jostle for food, she

would come up

at the rear every time.

would be convenient

It

for a

woman

to have

some man

see to

haunch

after the hunting was over and some other man didn't take it away from her. A primitive hunter would scarcely do this out of humanitarian philosophy; he would have to be bribed into it. I it

that she was thrown a

then see to

it,

suppose you're is

further, that

all

ahead of

me

in guessing that the obvious bribe

sex. I

visualize a

Man

and

Stone Age treaty of mutual assistance between

Woman—sex

for

food—and

togetherness, children are reared

as a result of this kind of

and the generations continue.*

an anthropologist named Charlotte O. Kursh long and fascinating letter that made it quite clear that I had dreadfully oversimplified the situation described here, that hunting was not the only food-source, and that questions of status were even more important than sex. Once one substituted "status-for-food" for "sex-for-food" she found she tended to agree with what followed. So, with this warning to take my anthropology with a grain of salt, let's continue. * After this article appeared,

wrote

me a

UNCERTAIN, COY, AND HARD TO PLEASE

235

don't see that any of the nobler passions can possibly have

I

had anything to do with

doubt that anything we would

this. I

recognize as "love" was present in the Stone Age, for romantic love

seems to have been a rather late invention and to be anything

but widespread even today.

once read that the Hollywood no-

(I

romantic love was invented by the medieval Arabs and

tion of

was spread

own Western

our

to

society

by the

Provencal

troubadours.)

As seem

for the concern of a father for his children, forget

definite indications that

men

it.

There

did not really understand the

connection between sexual intercourse and children until nearly historic times.

Mother

love

may have

pleasure of suckling, for instance) father love, however real

it

may

be,

Although the arrangement of sex sonable quid pro quo,

it isn't. It is

its

but is

basis in physiology (the I

strongly suspect that

cultural in origin.

for food

seems a pretty

rea-

a terribly unfair arrangement

because one side can break the agreement with impunity and the other cannot. If a

woman

punishes by withholding sex and a

by withholding food, which contrary, a

week without

food. Furthermore, a

what he wants by

sex

side will

week without

a lot easier than a

is

man

win out? Lysistrata to the

man who tires of this mutual woman can't.

strike

can take

force; a

seems to me, then, that for definite physiological reasons,

It

the original association of

man

one, with

men and women was a strictly unequal and woman in the role of

in the role of master

slave.

This

is

not to say that a clever woman, even in Stone Age times,

might not have managed to wheedle and her have her

own

way.

And we

all

know

man

cajole a

that this

is

into letting

certainly true

nowadays, but wheedling and cajolery are slave weapons.

Proud Reader, are a you

try to

man and

this,

I

what happens

letting

to your self-respect.

you,

would suggest

wheedle and cajole your boss into giving you a

wheedle and cajole a friend into see

don't see

If

raise,

or

you have your way, and

THE SOLAR SYSTEM AND BACK

236

In any master-slave relationship, the master does only that portion of the all else is

work that he

do or that the

reserved for the slave. It

duties not only slaves'

likes to

work

is

by custom but by

as unfit for free

men

slave

stern social law

the

"little-muscle."

the "big-muscle" work because he would have to and

women would

then do the "little-muscle" work. Let's face

(not always) a good deal for

this is usually

slaves*

which defines

to do.

Suppose we divide work into "big-muscle" and

Men would do

cannot do;

indeed frozen into the

men

it;

because there

is

more "little-muscle" work to do. ("Men work from sun to sun; women's work is never done," the old saying goes.) Sometimes, in fact, there is no "big-muscle" work to do at all. In that case the Indian brave sits around and watches the squaw far

work—a

situation that

and watch

is

true for

their non-Indian

course, that as

many

non-Indian braves

who

squaws work.* Their excuse

sit

of

is,

proud and gorgeous males they can scarcely be

ex-

pected to do "women's work."

The

social

apparatus of man-master and woman-slave was car-

ried right into the

most admired cultures of antiquity and was

never questioned there.

women tic

To

the Athenians of the Golden Age,

were inferior creatures, only dubiously superior to domes-

animals, and with nothing in the

cultivated Athenian,

it

seemed

way of human

virtually

rights.

self-evident

To

the

that male

homosexuality was the highest form of love, since that was the only

way

equal.

in

but so what;

As

which a human being (male, that

Of course, if

if

is)

could love an

he wanted children, he had to turn to a woman,

he wanted transportation, he turned to

for that other great culture of the past, the

his horse.

Hebrew,

it

is

quite obvious that the Bible accepts male superiority as a matter

of course. It

is

not even a subject for discussion at any point.

Adam and Eve, it has done woman's misery than any other book in history. The tale has enabled dozens of generations of men to blame everything on In fact, by introducing the story of

more

for

* Of course, if they are too chivalrous to watch a woman do all the work, they can always close their eyes. That will even give them a chance to sleep.

237

women.

It

made

has

would

men

of the

my-

in terms that a miserable sinner like

mad dogs. commandments themselves, women

In the ten

casually

are

and inanimate.

of property, animate

Exodus 20:17: "Thou

in

holy

hesitate to use in referring to

lumped with other forms says,

many

possible for a great

women

past to speak of self

it

It

shalt not covet thy neighbour's

house, thou shalt not covet thy neighbour's wife, nor his manservant, nor his maidservant, nor his ox,

that

is

Nor

nor his

ass,

nor any thing

thy neighbour's/'

New

the

is

quotations

I

Testament any

better.

can choose from, but

There are a number of

will give

I

you

this

one from

Ephesians 5:22-24: "Wives, submit yourselves unto your bands, as unto the Lord. For the husband

even as Christ

is

the wives be to their

This seems to

I

of

me

own husbands

hus-

is

the saviour of

subject unto Christ, so let

in every thing."

to aspire to a change in the social arrange-

man/woman from

master/slave to God/creature.

don't deny that there are

New

is

own

the head of the wife,

the head of the church: and he

the body. Therefore as the church

ment

is

many

passages in both the

Old and

Testaments that praise and dignify womankind. (For

ample, there

the

is

Book

of Ruth.)

The

trouble

is,

ex-

though, that in

the social history of our species, those passages of the Bible which

taught feminine wickedness and inferiority were by far the more

To the self-interest that led men to tighten the chains women was added the most formidable of religious in-

influential.

about

junctions.

The

situation has not utterly

Women in our

its

essence, even

now.

have attained a certain equality before the law—but only

own

shameful

changed in

Think how woman, however intelligent and educated, national election until 1920— despite the fact that

century, even here in the United States.

it is

that no

could vote in a

the vote was freely granted to every drunkard and moron, pro-

vided only that he happened to be male.

THE SOLAR SYSTEM AND BACK

238

women can own bodies— all the

Yet even so—though even

own

their

and hold property, and

vote,

social apparatus of inferiority

remains.

Any man can logical,

tive, refined rather

add

can't

you that a

tell

woman

intuitive rather than

is

emotional rather than reasonable, finicky rather than crea-

at mice,

a

and

Because

than vigorous. They don't understand

column of

figures, drive cars poorly, shriek

on and

so

women are men

equal share with

on and so on.

so

all

politics,

with terror

how

these things

in the

can they be allowed an

important tasks of running industry,

government, society?

Such an attitude

is self-fulfilling,

too.

We begin by teaching a young man that he women, and

this

top half of the

is

comforting for him.

human

race,

this

personal self-respect but his very

than a particular interested, she

if

man

must

a in

superior to

may

be.

notion threatens not only his

virility.

woman happens

whom

young

automatically in the

is

whatever his shortcomings

Anything that tends to disturb This means that

He

is

she

is

(for

never, for her very

be more intelligent

to

some arcane reason)

life,

reveal the fact.

No

sexual attraction can then overcome the mortal injury he receives in the very seat

On

and core of

his

the other hand, there

man

in the sight of a

self.

It is for

is

masculine pride, and she loses him.

something

woman who

that reason that a

is,

silly

infinitely relieving to a

manifestly, inferior to him-

woman

seems "cute."

The

more pronouncedly male-chauvinistic a society the more highly valued is silliness in a woman. Through long centuries, women have had to interest men somehow, if they were to achieve any economic security and social status at all, and so those who were not stupid and silly by nature had to carefully cultivate such stupidity and silliness until it came natural and they forgot they ever were intelligent. It is my feeling that all the emotional and temperamental distinctions between men and women are of cultural origin, and that

UNCERTAIN, COY, AND HARD TO PLEASE

239

they serve the important function of maintaining the

man/

woman It

master/slave arrangement.

seems to

me

that any clear look at social history shows this

and shows, moreover, that the feminine "temperament" jumps through hoops whenever that

is

necessary to suit man's con-

venience.

What was its

delicacy

ever

more feminine than Victorian womanhood, with

and modesty,

incredible refinement

to

and

its

blushes and catchings of breath,

its

constant need for the smelling

overcome a deplorable tendency to

sillier

Was

faint?

toy than the stereotype of the Victorian

Homo

ever a greater insult to the dignity of

But you can

see

why

the Victorian

there ever a

woman; was

work

when among

for her to

do

(or a rough approxIt

was

the upper classes, there was no "little-muscle"

since servants did

her do nothing. Firmly,

make-work nothings

men had

it.

men

her use her spare time in joining

Women

there

sapiens?

woman

imation of her) had to exist in the late nineteenth century. a time

its

salts

The

was

to let

have

her do nothing (except for such

embroidery and

as

alternative

in their work, or to

hack piano-playing).

were even encouraged to wear clothes that hampered

their physical

movements

to the point

where they could scarcely

walk or breathe.

What

was

left to

them, then, but a kind of ferocious boredom

that brought out the worst aspects of the

and made them

human temperament,

so unfit an object even for sex, that they were

carefully taught that sex

was

dirty

and

evil so that their

husbands

could go elsewhere for their pleasures.

But in this very same era, no one ever thought of applying the same toy-dog characteristics to the women of the lower classes. There was plenty of "little-muscle" work for them to do and since they had no time for fainting and refinement, the feminine

temperament made the necessary adjustment and they did without either fainting or refinement.

The

pioneer

women

of the

American West not only cleaned

THE SOLAR SYSTEM AND BACK

24O

house, cooked, and bore baby after baby, but they grabbed up

when

rifles

to fight off Indians

were

also hitched to the plow on such occasions as the horse

needed a

necessary.

strongly suspect they

I

or the tractor was being polished.

rest,

And

this

was

in

Victorian times.

We

see

women

just aren't

know how I

was a

then

it

them

about us even now.

it all

little

bank

There was a time

women

When

all

tellers.

Now

90 per cent of figures

and

all.

nurses were males because everyone

knew

were simply too delicate and refined for such work.

the economic necessities

made

turned out they weren't

as nurses,

it

after

(Now

all.

When

were male for that very reason. But

and apparently they can add up

balance checkbooks after

that

article of faith that

dears can't balance a checkbook.

tellers

got hard to hire male bank

are female

an

any good at even the simplest arithmetic. You

those cute

kid, all

It's

nursing

is

it

important to hire females

all

that delicate and refined

"woman's work" that

a

proud

man

wouldn't do.)

Doctors and engineers are almost always of social or economic crunch

men— until some

comes— and then

sort

the female temper-

ament makes the necessary change and, as in the Soviet Union, women become doctors and engineers in great numbers. What it amounts to is best expressed in a well-known verse by Sir Walter Scott:

O

woman!

in our hours of ease.

Uncertain, coy, and hard to please, •





When pain and anguish wring A ministering angel thou! Most women seem ful tribute to

to think this

them, but

of the fact that

I

when man

is

think that is

relaxing

the brow,

a very touching it is

and wonder-

a rather bald exhibition

he wants a toy and when he

UNCERTAIN, COY, AND HARD TO PLEASE in trouble

is

he wants a

slave

and woman

on instant

is

241 call for

either role.

What

if

ing angel?

But for

let's

pain and anguish wring her brow?

Why, not

women's

woman who

another

slip to

votes,

the male chauvinists said that this would

women had no

would merely be manipulated by by any

her minister-

the other extreme either. During the fight

wreck the nation since

priests, or

Who's

hired for the occasion.

is

political

their

feeling for politics

and

menfolks (or by their

quack with a scalpful of

curls

and a

mouthful of teeth). Feminists, on the other hand, said that their gentleness all graft,

It

when women brought

and refinement and honesty

corruption,

to the polling booth,

and war would be brought

to

an end.

You know what happened when women got the vote? Nothing. turned out that women were no stupider than men—and no

wiser, either.

What

of the future? Will

Not

basic conditions continue as they have ever since

if

sapiens

became

a species.

women

Men

gain true equality?

Homo

won't voluntarily give up their ad-

vantage. Masters never do. Sometimes they are forced to do so by

one

violent revolution of

sort or another.

forced to do so by their wise foresight of a

Sometimes they are

coming violent

revolu-

tion.

An

individual

may

up an advantage out of a mere sense of always in the minority and a group as a

give

decency, but such are

whole never does. Indeed, in the present case, the strongest proponents of the status

quo are the women themselves

They have played the

role so long they

the wrists and ankles

the chains were struck

grown

if

so used to the petty rewards

fered elbow, the smirk

be

silly)

and

leer,

would

feel chills

off.

And

about

they have

(the tipped hat, the of-

and, most of

that they won't exchange

most of them).

(at least

them

all,

the freedom to

for freedom.

Who

is

THE SOLAR SYSTEM AND BACK

242

woman who

hardest on the independent-minded

conventions? Other

women,

defies the slave-

of course, playing the fink

on behalf

men.

of

Yet things

What

was the

women? 1. Most men most women. So?

change even

will

woman's

that underlie

What

mayhem

first

are physically larger

when only

Rape

And

does

it

a

Is

and physically stronger than a crime

and

so

is

physical

women. That doesn't does keep them from being

it

game they once

men woman too

matter that

economic sense?

Does she have

is

men and

directed against

stop such practices altogether, but

the universal masculine

between

difference

essential

of that today.

even

because the basic conditions

so,

historic position are changing.

were.

are larger

and

stronger, in the

small and

weak

to earn a living?

to crawl into the protecting neck-clutch of a male,

however stupid or

haunch of the

he may be, for the equivalent of the

distasteful

kill?

Nonsense! "Big-muscle" jobs are steadily disappearing and only "little-muscle" jobs are left.

push buttons and

let

We

don't dig ditches any more,

machines dig ditches. The world

computerized and there

is

nothing a

man

is

we

being

can do in the way of

pushing paper, sorting cards, and twiddling contacts, that a

woman

can't

do

just as well.

In fact, littleness

may be

at a

premium. Smaller and slenderer

may be just what is wanted. More and more, women will learn

fingers

sex

and love

nothing that quickly do

for love,

and nevermore

will dignify sex

they need only offer sex for sex for food.

more than

this

I

can think of

change, or more

away with the degrading master/slave existence of "the

double standard."

But how about the second 2.

Women

don't.

difference:

get pregnant, bear babies,

and suckle them.

Men

UNCERTAIN, COY, AND HARD TO PLEASE frequently hear

I

tell

that

women

have a "nest-building"

they really want to take care of a

stinct, that

Maybe

themselves for his sake.

so,

243 in-

man and immolate

under conditions

as they used

But how about now?

to be.

With

the population explosion becoming more and more of a

mankind, we

cliff-hanger for all

before the end of the cen-

will,

have evolved a new attitude toward babies or our culture

tury,

will die. It will

become

The

babies. will lift

nomic

mean even more than

will

Thanks

pressure.

to the

pill,

without the abandonment of

lifted

become

stifling social pressure to

and that

woman

perfectly all right for a

women

This doesn't mean

not to have

a "wife

and mother"

the lifting of the eco-

the burden of babies can be sex.

won't have babies;

it

means merely

they won't have to have babies.

In

female slavery and the population explosion

fact, I feel that

go hand in hand. Keep a

man

will feel safe

woman

in subjection

to keep her "barefoot

is

and the only way a

and pregnant."

If

she

has nothing to do except undignified and repetitive labor, a

woman

will

want baby

after

baby

as the only escape to

something

else.

On

the other hand,

explosion will stop of sacrifice their

say

freedom

"No" too

tried,

but

where the

make women truly free and the population its own accord. Few women would want to for the sake of

must be

it

completely free for the

cycles

I

babies.

significant that the birth

social position of

women

In the twenty-first century, then,

Nor am

numerous

quickly; feminine freedom has never

first

is

I

rate

And

don't

been

truly

is

highest

lowest.

predict that

women

will

be

time in the history of the species.

afraid of the counter-prediction that all things go in

and that the

pation will give Effects can

way

be

clearly visible trend

toward feminine emanci-

to a swing back to a kind of neo-Victorianism.

cyclic,

yes—but only

if

causes are cyclic,

and the

THE SOLAR SYSTEM AND BACK

244

thermonu-

basic causes here are non-cyclic, barring world-wide clear war.

In order for the pendulum to swing back toward feminine slavery, there

that only

would have

men

starvation without a

be an increase in "big-muscle jobs"

to

Women

could do.

man

work

to

must begin once more

to fear

them. Well, do you think

for

the present trend toward computerization and social security will reverse itself short of global catastrophe? Honestly?

In order for the pendulum to swing back, there would have to

be a continuation of the desire

way

dren. There's no other

for large families

of keeping

and

women

lots of chil-

contented with

her slavery on a large scale (or too busy to think about

it, which same thing). Given our present population explosion and the situation as it will be by 2000, do you honestly expect women to be put to work breeding baby after baby?

amounts

to the

So the trend toward woman's freedom There's the beginning of

Do

it

right

is

irreversible.

now and

it is

well established.

you think that the present era of increasing sexual permissive-

ness (almost everywhere in the world)

down

in our

moral

fiber

and that

a

is

little

just a

temporary break-

government action

will

restore the stern virtues of our ancestors?

Don't you believe will

continue to be

it.

Sex has been divorced from babies, and

so, since sex can't possibly

babies can't possibly be encouraged.

but the "sexual revolution"

Or

Vote

for

whom

man.

you please

will continue.

take even something so apparently trivial as the

hairiness in

it

be suppressed and

new

fad of

grown a pair of absolutely magnificent

(I've just

change in

sideburns myself.)

Sure,

really stands for is

the breakdown of

it

will

details,

but what

trivial distinctions

it

between

the sexes. It is

indeed this which disturbs the conventional. Over and

over, I hear

them complain that some

looks just like a

any more!"

girl.

And

then they

say,

particular long-haired

"You

can't

tell

boy

them apart

UNCERTAIN, COY, AND HARD TO PLEASE This always makes

boy from a

me wonder why

where the sex makes a

in view

neer or an After

is

if it

were

is

You

make

Catholic, Protestant, or

or stupid.

important to

really

use of Nature's distinction? That

tell

the sexes apart at

why not

the difference

is

sometimes extreme.

Well, then, should

all

who

Any change

beards.

if

women,

poor thing,

wife,

men grow

beards? Yet the very same con-

unsettles them,

so

man,

also object to

when change becomes

must be ignored.

men and long hair for men and skirts for women,

this fetish of short hair for

or, for

that matter, pants for

men and

shirts for

(My

blouses for

women?

Why a set of artificial Why the sense of

tinctions to exaggerate the natural ones?

turbance

Can

it

when the

No

dis-

dis-

distinctions are blurred?

be that the loud and gaudy distinction of dress and hair

between the two sexes ship?

On

women;

she tried.)

object to long hair on a

necessary, conventional people

But why

not long hair since both

always have more facial hair than

couldn't grow sideburns even

ventional people

is

grow hair of approximately equal length.

men

the other hand,

a

can't tell at a

the distance of several blocks with one quick glance,

sexes in all cultures

tell

a piano player or a poker player, an engi-

artist, intelligent

all,

so important to

difference.

glance whether a particular person Jew; whether he/she

it is

one has some personal object

at a glance, unless

girl

245

is

another sign of the master-slave relation-

master wants to be mistaken for a slave at any distance,

or have a slave mistaken for a master, either. In slave societies, slaves are always carefully distinguished

Manchus ruled

(by a pigtail

ruled China, by a yellow Star of David

when the Nazis

Germany, and so on). We ourselves tend to most conspicuous non-female slaves had a

since our

skin color

and required very

little else

In the society of sexual equality that

be a blurring of that

is

already

artificial distinctions

on the way. But

so

to is

when the forget this distinctive

mark them. coming, then, there

between the what?

A

will

sexes, a blurring

particular

boy

will

THE SOLAR SYSTEM AND BACK

246

know who is

his particular girl

is

and

vice versa,

and

if

someone

else

not part of the relationship what does he/she care which

is

which? I

say

it

pened I

we can't beat the trend and we should may even be the most wonderful thing

say

to

it.

I

that has ever hap-

mankind.

think the Greeks were right in a

to love an equal.

when we

therefore join

And

if

way and

that be so,

that

why not

heterosexuals can have love at

its

it is

much

better

hasten the time

best?

N3